DNA preserved after a 1989 attack eventually led investigators to Frederick Louis Tanzer, who later admitted committing the crime.
CINCINNATI, OH — For nearly 35 years, Dana Beatty did not know the identity of the masked man who broke into her Cincinnati condominium and raped her in 1989. The answer eventually emerged through preserved DNA, her daughter’s determination to revive the investigation and a discarded coffee cup collected by federal investigators.
The investigation identified Frederick Louis Tanzer, a Cincinnati-area physician whom Beatty already knew socially. Tanzer later admitted committing the 1989 attack, according to federal prosecutors. But because the statute of limitations on the original crimes had expired around 1995, authorities could not prosecute him for the attack. Instead, federal prosecutors charged him after he made false statements to investigators about his contact with Beatty. He pleaded guilty to three false-statement counts in September 2025 and was sentenced in January 2026 to 15 years in federal prison, the statutory maximum.
The case began Aug. 1, 1989, when Beatty, then 29 and working for IBM, returned to her condominium in Cincinnati’s Columbia-Tusculum neighborhood. She noticed signs that something was wrong inside. A masked man dressed in black confronted her with a knife and restrained her. According to federal court records and prosecutors, the attacker sexually assaulted Beatty repeatedly during an ordeal lasting about five and a half hours. After he left, she freed herself and sought help from a neighbor.
Evidence collected after the attack would prove critical decades later. A hospital examination preserved biological evidence containing the attacker’s DNA, while investigators also collected other evidence. But police were unable to identify the attacker at the time, and the case remained unsolved for decades. Beatty went on with her life, marrying and becoming a mother, while the identity of the man who attacked her remained unknown.
A major change came after Beatty’s daughter, Andra, learned about advances in DNA technology being used to investigate old crimes. In 2023, she contacted the Ohio Attorney General’s Office seeking help with her mother’s case, according to Beatty’s account to WLWT. The inquiry eventually reached Cincinnati cold-case Detective Jeffrey Smallwood and helped bring renewed attention to evidence preserved from the 1989 investigation.
Investigators used newer forensic techniques to develop a lead that eventually focused attention on Tanzer. The possibility initially surprised Beatty. She knew Tanzer through his former wife, who had been Beatty’s friend, and Beatty had attended their wedding. But investigators still needed DNA directly associated with Tanzer before they could confirm whether the genetic lead pointed to the man responsible for the attack.
That evidence came from an ordinary coffee cup. On April 9, 2024, FBI surveillance personnel followed Tanzer to a Bureau of Motor Vehicles office in Milford, according to court records reported by WLWT. Tanzer carried a Starbucks cup into the building and later threw it away. An FBI specialist retrieved the discarded cup. DNA recovered from it was tested and matched the DNA profile preserved from evidence connected to the 1989 attack. Federal prosecutors later confirmed that the FBI and Cincinnati Police Department used DNA from Tanzer’s coffee cup to establish the match.
The identification did not allow prosecutors to file charges for the 1989 sexual assault. Federal authorities said the statute of limitations applicable to the crimes had expired approximately six years after the attack. Investigators instead continued examining the case and interviewed Tanzer in December 2024. During questioning by an FBI agent and a Cincinnati police detective, Tanzer denied seeing or interacting with Beatty on the day of the attack, according to prosecutors. Those statements conflicted with the DNA evidence investigators had already obtained.
Federal agents arrested Tanzer on Dec. 11, 2024, on a charge of making false statements. A federal grand jury later returned a six-count indictment involving false statements and writings. The federal case did not charge Tanzer with rape. In September 2025, Tanzer pleaded guilty to three counts of making false statements to federal agents. His plea documents also included his admission that he had committed the 1989 attack.
U.S. District Judge Michael J. Newman sentenced Tanzer, then 67, on Jan. 28, 2026, to 180 months in prison. Each of the three false-statement counts carried a maximum five-year sentence. The Justice Department said Tanzer had remained in custody since his December 2024 arrest. The sentence punished the federal false-statement offenses rather than the sexual assault itself, which could no longer be prosecuted because of the expired statute of limitations.
Beatty has chosen to be publicly identified. The U.S. Attorney’s Office for the Southern District of Ohio, which generally does not name crime victims, said it identified her at her request. She has spoken publicly about the investigation and credited her daughter’s decision to pursue the old case with helping revive the search for the man who attacked her. Beatty has also said she hopes her experience draws attention to statutes of limitations involving violent sexual crimes.
The case ultimately turned on evidence preserved for decades and forensic technology unavailable to investigators in 1989. Tanzer remains imprisoned on the federal false-statement convictions. Although he was never prosecuted for the 1989 rape because the legal deadline had passed, his DNA identification and subsequent admission provided Beatty with the answer she had waited decades to receive.
Author note: Last updated Oct. 3, 2026.