Clark Perry Baldwin: The Interstate Murders and the DNA Evidence That Ended a Decades-Long Mystery
Clark Perry Baldwin was an American long-haul truck driver whose work carried him across the United States and placed him on the same interstate highway system where several women were attacked and killed during the early 1990s. For nearly three decades, murders in Tennessee and Wyoming remained separate cold cases, with two of the victims unidentified. Advances in forensic DNA testing eventually showed that biological evidence from three homicide investigations came from the same man. Investigative genetic genealogy then led authorities to Baldwin.
Baldwin was arrested at his home in Waterloo, Iowa, on May 6, 2020. He was charged with the murder of Pamela Rose Aldridge McCall in Tennessee and with the murders of two unidentified women in Wyoming who were then known as "Bitter Creek Betty" and "I-90 Jane Doe." Both Wyoming victims were eventually identified as Irene Vasquez and Cindi Arleen Estrada.
Baldwin was ultimately convicted of first-degree murder for McCall's death in Tennessee on May 2, 2025, and sentenced to life imprisonment. He never went to trial for the Wyoming homicides. Baldwin died in a Tennessee hospital on July 18, 2025, after suffering a heart attack, ending the possibility of criminal trials for the deaths of Vasquez and Estrada.
Background and Life as a Long-Haul Truck Driver
Clark Perry Baldwin was born on August 22, 1961, in Iowa and spent part of his youth in Nashua. As an adult, he became an over-the-road truck driver, an occupation that allowed him to travel great distances and move regularly from one state to another. This became important to investigators when they began examining whether murders hundreds of miles apart might have been committed by the same offender.
By the early 1990s, Baldwin was driving commercially across the country. The crimes eventually connected to him occurred near major interstate highways and involved women who were vulnerable while traveling or whose bodies were left in isolated areas accessible to truck traffic. Investigators later considered Baldwin's occupation and extensive travel history when reviewing additional unsolved homicides.
The February 1991 Attack on Mary Ann Newton
One of the most important incidents in understanding Baldwin's later murder prosecution occurred shortly before Pamela McCall was killed. On February 18, 1991, 21-year-old Mary Ann Newton was traveling by hitchhiking when she accepted a ride from Baldwin, who was driving a commercial truck. Newton had entered Baldwin's truck in Oklahoma, and the two eventually traveled west on Interstate 40 toward Texas.
According to Newton's testimony and the original investigation, Baldwin attacked her inside the sleeping compartment of the truck after they stopped in the Texas Panhandle. Newton said she regained awareness while Baldwin was sexually assaulting and strangling her. Her wrists had been restrained and her mouth had been obstructed and taped.
Newton fought to survive. Baldwin eventually released her restraints and, in an extraordinary sequence of events, gave her access to a handgun. Newton took control of the weapon and ordered Baldwin to continue driving until she saw a place where she could escape. When she spotted a gas station, she forced him to pull over, threw the firearm back toward the truck and ran for help.
Police investigated Baldwin at the time. He made statements acknowledging that he had forced sexual activity upon Newton and had restrained her, but the prosecution did not result in a conviction and the case was ultimately dismissed for failure to prosecute. More than three decades later, Newton testified at Baldwin's Tennessee murder trial. Her account was important because of the similarities between her attack and evidence surrounding the women who did not escape.
Murder of Pamela Rose Aldridge McCall
On March 10, 1991, only weeks after the attack on Newton, motorists and authorities encountered another violent crime connected with interstate travel. The body of Pamela Rose Aldridge McCall was discovered at approximately 12:30 p.m. in a wooded area near Saturn Parkway and the Port Royal Road exit in Spring Hill, Tennessee. Her body was about 100 feet from the roadway.
McCall had suffered injuries to her face and neck, and investigators found her clothing disturbed and damaged. An autopsy determined that she had been strangled. Evidence also indicated that she had been sexually assaulted. McCall was approximately 24 weeks pregnant, and her unborn daughter died with her.
Investigators examining the roadside scene documented tire or skid marks believed to have been made by a tractor-trailer near the place where McCall's body had been left. Witness information also suggested that McCall had been traveling with or had encountered a truck driver shortly before she was killed.
Biological evidence was preserved from McCall's body and clothing. The forensic technology available in 1991 could not identify the killer, but investigators retained the evidence. That decision became critical nearly three decades later.
Irene Vasquez - Formerly Known as "Bitter Creek Betty"
On March 1, 1992, a truck driver stopping near the Bitter Creek area along Interstate 80 in Sweetwater County, Wyoming, discovered the body of a woman lying face down in the snow. The location was approximately 40 miles east of Rock Springs and was easily accessible from one of the nation's major east-west trucking routes.
The woman was unidentified and became known for decades as "Bitter Creek Betty." Investigators determined that she had been the victim of a homicide and had suffered significant head and facial injuries, strangulation and sexual assault. Her body had been exposed to winter conditions, making it impossible to establish a precise date of death.
The verified date of discovery was March 1, 1992. Her exact date of death remains unknown. Investigators estimated that she may have been killed or deposited in the area sometime between approximately October 1991 and February 1992.
The victim had several distinctive characteristics, including a rose tattoo on her breast, a surgical scar and jewelry. Despite widespread attempts to identify her, she remained nameless for decades.
Forensic genetic genealogy eventually restored her identity. She was identified as Irene Vasquez. Investigators learned that family members had not heard from Vasquez since approximately 1990. Her identification was established years after Baldwin's arrest and was publicly disclosed in 2025.
Cindi Arleen Estrada - Formerly Known as "I-90 Jane Doe"
Only weeks after Vasquez's body was discovered, another woman was found beside a Wyoming interstate. On April 13, 1992, transportation workers discovered a partially decomposed and mummified female body near milepost 5 on the west side of Interstate 90 in Sheridan County, only a short distance south of the Montana border.
The woman was young and was approximately ten weeks pregnant when she died. Evidence showed that she had been sexually assaulted and subjected to blunt-force violence. Authorities classified her death as a homicide, although decomposition prevented examiners from determining a single definitive mechanism of death.
Her exact date of death has never been established. Investigators believed she had probably been killed weeks before her April 13, 1992 discovery, with February 1992 frequently cited as the likely period of death.
For more than 33 years she was referred to as "I-90 Jane Doe" or the Sheridan County Jane Doe. On July 17, 2025, the Wyoming Division of Criminal Investigation announced that DNA comparison with her biological family had identified her as 21-year-old Cindi Arleen Estrada, originally from California.
The announcement came at an extraordinary moment in the case. Baldwin, who was awaiting transfer to Wyoming to face a first-degree murder charge for Estrada's death, died the following day.
Victims Linked to Clark Perry Baldwin
- Pamela Rose Aldridge McCall - Date of death/crime: March 10, 1991. Location: Spring Hill, Tennessee, near Saturn Parkway and Port Royal Road. McCall was strangled and sexually assaulted. She was approximately 24 weeks pregnant. Baldwin was convicted of her first-degree murder on May 2, 2025.
- Pamela McCall's unborn daughter - Date of death: March 10, 1991. Location: Spring Hill, Tennessee. The approximately 24-week pregnancy ended as a result of the attack that killed McCall. Baldwin was initially charged in connection with both deaths, although his confirmed 2025 first-degree murder conviction was for Pamela McCall's killing.
- Irene Vasquez, formerly "Bitter Creek Betty" - Exact date of death unknown; investigators estimated a period between approximately October 1991 and February 1992. Body discovered March 1, 1992. Location: Bitter Creek area along Interstate 80, approximately 40 miles east of Rock Springs, Sweetwater County, Wyoming. She was sexually assaulted and suffered strangulation and severe traumatic injuries. Baldwin was charged with her murder but died before trial.
- Cindi Arleen Estrada, formerly "I-90 Jane Doe" - Exact date of death unknown; believed to have died weeks before her body was found and possibly during February 1992. Body discovered April 13, 1992. Location: Interstate 90 near milepost 5, Sheridan County, Wyoming, close to the Montana border. Estrada was 21 and approximately ten weeks pregnant. She had been sexually assaulted and subjected to homicidal violence. Baldwin was charged with her murder but died before trial.
The DNA Connection Between Tennessee and Wyoming
The three homicide investigations originally had no obvious reason to be treated as a single series. McCall had been killed in Tennessee, while the two unidentified Wyoming women were discovered roughly 400 miles apart from one another. Years of conventional police work failed to identify either the Wyoming victims or their killer.
Forensic DNA changed the investigation. Testing of evidence from the two Wyoming murders established that the same male DNA contributor was connected to both crime scenes. When investigators in Tennessee reopened McCall's case in 2019 and submitted preserved evidence for modern testing, the male DNA profile from her homicide matched the profile associated with the Wyoming cases.
For the first time, investigators knew that one man was linked through biological evidence to three women killed along major interstate corridors in two states.
Investigative Genetic Genealogy Leads to Baldwin
Investigators then turned to investigative genetic genealogy. Genetic information associated with the unknown killer was compared against data capable of identifying relatives. The process narrowed the possible family lines until investigators began focusing on Clark Perry Baldwin.
Authorities still needed a direct sample from Baldwin. FBI investigators conducting surveillance in Waterloo obtained discarded biological material associated with him, including material recovered from his trash. Investigators also obtained DNA after Baldwin used a shopping cart at a Walmart store.
Laboratory testing matched Baldwin's DNA to the male profile connected with the Tennessee and Wyoming homicide evidence. The result transformed three decades-old investigations into active murder cases with an identified suspect.
Arrest on May 6, 2020
On May 6, 2020, investigators from the FBI, Iowa Division of Criminal Investigation, Wyoming Division of Criminal Investigation and Tennessee authorities arrested Baldwin at his residence in Waterloo, Iowa.
Tennessee charged him in connection with the deaths of Pamela McCall and her unborn child. Wyoming authorities filed first-degree murder charges relating to the deaths of the women then still publicly known as Bitter Creek Betty and I-90 Jane Doe.
The states decided that Baldwin would face prosecution in Tennessee first. His murder case remained pending for years, partly because of delays associated with the COVID-19 pandemic and subsequent court proceedings.
The 2025 Murder Trial
Baldwin's Tennessee trial finally began in Maury County in April 2025. Prosecutors presented the decades-old physical evidence, modern DNA results, testimony about the investigation and evidence concerning Baldwin's movements and behavior.
Mary Ann Newton also appeared before the jury and described surviving Baldwin's attack in his truck in February 1991. Her testimony gave jurors an account from a woman who had personally experienced Baldwin's use of sexual violence and strangulation shortly before McCall was murdered.
On May 2, 2025, the jury found Clark Perry Baldwin guilty of first-degree murder in the killing of Pamela Rose Aldridge McCall. He was immediately sentenced to life imprisonment.
The Wyoming Cases Remained Untried
Following the Tennessee conviction, Wyoming prosecutors prepared to bring Baldwin west to face the murder charges involving Irene Vasquez and Cindi Arleen Estrada. The forensic case against him included the male DNA profile that had originally connected the two Wyoming homicides and that investigators said matched Baldwin.
However, a criminal trial never occurred. Because Baldwin died before the Wyoming cases could be presented to juries, he was never legally convicted of murdering Vasquez or Estrada. For accuracy, those two deaths should therefore be described as murders for which Baldwin was DNA-linked and charged, rather than murders resulting in convictions.
Possible Victim: Rhonda Anette Knutson
Investigators have also examined whether Baldwin could have been responsible for other unsolved killings. One of the most significant is the September 7, 1992 murder of 22-year-old Rhonda Anette Knutson in Iowa.
- Rhonda Anette Knutson - Date of death: September 7, 1992. Location: Phillips 66 convenience store on U.S. Highway 63 in the Williamstown/New Hampton area of Chickasaw County, Iowa. Knutson was working the overnight shift when she was bludgeoned to death. Witnesses had reported men associated with truck traffic in the store during the relevant period. Baldwin was living in nearby Nashua at the time. As of 2026, law enforcement had not ruled Baldwin out, but he was never charged with Knutson's murder and the case remains unsolved.
The Knutson homicide differs in important ways from the three interstate cases. She was killed inside her workplace rather than being discovered beside an interstate, and investigators found no evidence of sexual assault. There is also no publicly established DNA evidence connecting Baldwin to her murder. His geographic proximity, occupation and the circumstances surrounding the investigation caused authorities to examine him, but suspicion is not proof.
Tammy Jo Zywicki Was Investigated but Baldwin Was Not Considered Her Killer
Another well-known case briefly examined after Baldwin's arrest was the 1992 murder of 21-year-old college student Tammy Jo Zywicki. Zywicki disappeared after her car became disabled along Interstate 80 in Illinois on August 23, 1992, and her body was discovered in Missouri on September 1.
Because witnesses had described a truck near Zywicki's disabled vehicle and Baldwin had been a long-haul driver, investigators reviewed him as a possible connection after his 2020 arrest. Illinois State Police subsequently stated that Baldwin did not appear to have been involved in Zywicki's murder. She should therefore not be listed as one of Baldwin's victims.
Death of Clark Perry Baldwin
After his Tennessee conviction, Baldwin remained in custody while legal proceedings continued and Wyoming authorities prepared for eventual extradition. He suffered a heart attack in July 2025 and was taken to a Tennessee hospital.
Clark Perry Baldwin died on July 18, 2025. He was 63 years old and would have turned 64 the following month. His death occurred one day after authorities publicly announced that I-90 Jane Doe had finally been identified as Cindi Arleen Estrada.
Baldwin's death permanently prevented Wyoming prosecutors from putting the cases of Irene Vasquez and Cindi Estrada before juries. It also limited investigators' ability to question him about other unresolved homicides that occurred during the years when he traveled extensively as a truck driver.
Legacy of the Investigation
The Clark Perry Baldwin investigation illustrates how evidence preserved from apparently unrelated cold cases can acquire new significance decades later. When Pamela McCall was murdered in 1991 and Irene Vasquez and Cindi Estrada were found in Wyoming in 1992, investigators lacked the technology necessary to identify the man whose biological evidence had been left behind.
DNA eventually connected the murders across state lines. Investigative genetic genealogy narrowed the unknown profile to Baldwin's family, and discarded DNA obtained during surveillance provided the direct comparison investigators needed. Nearly 29 years after McCall's death, Baldwin was arrested, and 34 years after her murder, a Tennessee jury convicted him.
The investigation also restored the identities of two women who had spent decades known only by names assigned to their unidentified remains. "Bitter Creek Betty" became Irene Vasquez, and "I-90 Jane Doe" became Cindi Arleen Estrada. Although Baldwin's death prevented Wyoming from completing its prosecutions, forensic evidence gave investigators a common suspect, allowed the women to be identified and connected crimes that had once appeared to be isolated tragedies scattered across America's interstate highway system.
