A Pennsylvania man identified decades after two women were killed may not have been the only victim of a previously unknown serial offender, an expert warns. Investigators linked James Richard Clark Sr. to the 1970s murders through advances in DNA analysis.
During a Thursday news conference, Pennsylvania State Police named Clark as the man who sexually assaulted and strangled Brenda Ritter, 18, and Susan Rush, 21, in separate killings during the 1970s.
Rush disappeared on Nov. 24, 1976, after leaving a shopping mall, according to the City of Washington Police Department. She had planned to meet her family at church but never showed up. The following morning, Thanksgiving Day, her brother found her car parked along a street. Her body was later discovered inside the trunk.
Pennsylvania State Police identified James Richard Clark Sr., who died in 2023, as the man responsible for the killings of Brenda Ritter and Susan Rush in the 1970s. (Pennsylvania State Police)
Ritter vanished from her boyfriend’s home in 1977, police said. Her body was eventually found on a hillside, where investigators determined she had been sexually assaulted and strangled.
Clark died of natural causes on July 17, 2023, at age 66.
Investigators sent evidence from Ritter’s homicide to the state police crime lab in late 2008. The analysis generated a DNA profile belonging to an unidentified male. That profile was entered into the FBI’s Combined DNA Index System, or CODIS, where weekly searches produced no match. In May 2025, testing by Cybergenetics found that the same man was linked to both women’s deaths.
According to police, Clark left DNA evidence at both crime scenes. Improved testing by multiple laboratories, including Identifinders International, helped investigators identify him. Additional analysis later confirmed the connection.
Brenda Ritter, 18, disappeared from her boyfriend’s home in 1977. Police later found her on a hillside and determined she had been sexually assaulted and strangled. (Pennsylvania State Police)
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Police said Clark was 20 when Ritter was killed and 19 at the time of Rush’s death.
Pennsylvania State Police Cpl. James Petrosky said investigators believe Clark may have had additional victims.
“I believe that once you’re a serial killer, you’re always a serial killer. I believe there could potentially be more victims out there,” Petrosky said.
Dr. Kris Mohandie, a former Los Angeles Police Department psychologist and FBI behavioral-analysis consultant, told News Outlet that it is “normal” for the number of confirmed victims to represent only part of a serial killer’s suspected toll. New forensic tools, he said, frequently uncover links that were impossible to establish in earlier investigations.
“I think it’s normal and typical that the number of known cases is always lower than the number eventually detected,” Mohandie said. “These kinds of offenders often have more victims than the cases investigators have connected to them. In reality, serial offenders are usually responsible for more crimes than they are ever held accountable for.”
Susan Rush, 21, disappeared after leaving a shopping mall on Nov. 24, 1976. Police found her body the following morning in the trunk of her car. (Pennsylvania State Police)
Mohandie said serial killers can also stop offending for years. Some may believe investigators are closing in, while others become absorbed in family responsibilities or other aspects of daily life.
“There are many cases in which they become dormant—a cooling-off period—and that may happen because they realize continuing to offend will lead to their capture,” he said. “It can be a deliberate strategy to avoid being caught. A close call with investigators may also frighten them into going quiet for a time.”
