The approvals process for submitting DNA evidence proves time-consuming, as Columbus Police ready samples for “familial searches” of offender databases. A woman whose sister was murdered in the 1980s explains how forensic genealogy led to answers and reflects on the idea of closure. Martha Petry and Pat Sproat Loeliger reunite more than 50 years after the murder of their siblings and discuss their current thinking about the case’s solvability. A breakthrough occurs that leads to new hope for resolution.

Columbus Police agree to speak with Mary's identical twin sister, Martha Petry, and reveal they are waiting to submit DNA evidence for forensic genealogy analysis. First, they're working to rule out two other suspects. James Renner, a true crime author and founder of the nonprofit Porchlight Project, says a window for solving the case may be closing as forensic genealogy becomes increasingly regulated.

A woman who shared a ride to Columbus with Mary recalls Mary was adamant about waiting for Bill to pick her up from a hotel lobby, which Mary's brother finds puzzling. Podcast host Justin Glanville explores a possible connection between the crime and Mary's travels to France. Justin and Martha Petry struggle to make contact with the Columbus police.

Police and family members have long speculated that whoever killed Mary Petry and Bill Sproat may have known them. There were no signs of forced entry into the apartment, and the brutal nature of the killings indicates an emotional component. But Mary and Bill had no apparent enemies. An unexpected tip came in the mid-2000s, saying a religious figure in Mary's life wanted to punish her for considering pre-marital sex – a theory that Mary’s sister finds bizarre. Several retired police officers share their perspectives on the case, including submitting DNA evidence for matching in a state database.

The Columbus police make a surprise visit to Cleveland, and one of the surviving reporters who covered the murders of Mary Petry and Bill Sproat in 1970 shares details on the cold case. A forensic pathologist reviews the autopsy and coroner's reports to reveal possible discrepancies in the case.

A formal request is made to the Columbus Police Department for documents related to the murders of Mary Petry and Bill Sproat, inspiring an unexpected visit from detectives. Police reports begin to flesh out the timeline of the crime, and a tour of the Columbus apartment where the murders took place suggests how the murderer might have gained access. Bill’s sister Pat Sproat Loeliger shares her memories of Bill, including his love of French language and culture.

Growing up, I heard my parents talk about the grisly 1970 double homicide of their college friend Bill Sproat and Bill’s girlfriend, Mary Petry, near the The Ohio State University campus in Columbus. No arrests were ever made. The murders of Mary and Bill were so violent – reportedly involving a kitchen knife, wire hangers and a bowling ball – that they were compared to the Charles Manson cult killings of the previous year. Manson and his followers killed multiple people in California in 1969 and the savage crimes shocked the nation and turned him into a criminal icon. I wondered: In an age of ever-advancing DNA technology, is there new hope the case could be solved? My parents and I started with a road trip to talk to Mary’s identical twin sister, Martha Petry, who told us she still wants answers.

In 1970, Mary and Bill, two university students in love, were murdered in a Columbus, Ohio apartment, in a crime so brutal it drew comparisons to the Manson murders of the previous year. The case has never been solved. Host/Producer Justin Glanville and the sisters of the two victims work together to track down friends, witnesses to the original investigation and the Columbus police to understand why the case remains unsolved –despite the existence of solid DNA evidenceand the fact that police say they have a person of interest. Along the way, the three explore who really owns DNA collected at crime scenes –families or police? –and what it takes to bring new attention to a 50-year-old cold case in an era when police departments are struggling to attract new recruits and balance budgets.