New Hope in Missing Hudson Valley Girl Case

5 Years after a Hudson Valley woman disappeared while away at college, there may be new hope.

A former FBI agent says he thinks he knows what happened to Indiana University sophomore Lauren Spierer who went missing on June 3, 2011.

The 20-year-old from Edgemont was last seen around 4:30 a.m. on a Bloomington street after leaving a friend’s off-campus apartment.

Brad Garrett tells ABC's "20/20" that a source told him Spierer died from a drug overdose and, in a panic, her friends disposed of her body in the Ohio River.

The friends, all men between 18 and 20-years-old at the time, have not been cooperative in the investigation.

Garrett’s source is a fellow inmate serving time with Corey Hamersley at Indiana State prison. Hamersley was a student at Indiana with Lauren. He’s serving a 24 year prison sentence after unloading 32 shots on a house and car, and then firing at police while high on drugs.

The source told ABC that while playing cards with Hamesley, Lauren’s image appeared on the screen he said, "I knew the guys that did that.They were drinking and doing ecstasy. She OD'ed. It scared them. They didn't know what to do with her and they took her down to the Ohio River... and got rid of her... disposed of her body.”

Hamersley denied making the claims in a follow-up interview with authorities. Garret believes the theory makes sense.