Law enforcement seeks help to identify barns in BTK serial killer cold case investigations

A law enforcement team in northeast Oklahoma believes the prolific serial killer known as "BTK" may be responsible for several additional unsolved missing person and homicide cases. Now they're hoping the public can help them identify barns and silos in Oklahoma, Kansas and Missouri that the self-proclaimed BTK killer Dennis Rader sketched in never-before-seen detailed drawings.

Last month, the Osage County Sheriff's Office publicly confirmed it was investigating Rader as the "prime suspect" in a 1976 cold case in their jurisdiction and several other unsolved crimes across three states.

The investigators believe the killer may have buried 16-year-old Cynthia Dawn Kinney in a barn near the Kansas-Oklahoma border. Kinney was last seen at a laundromat in Pawhuska, Oklahoma, in 1976. Her body has never been found.

CNN obtained images of Rader's drawings, which were first recovered by law enforcement after his arrest in 2005.

Rader pleaded guilty to 10 murders that took place from the 1970s to the 1990s in Wichita, Kansas, for which he's serving 10 consecutive life sentences in a state prison. He suggested in a letter found long before his capture that he should be called "BTK," short for "bind, torture, kill."

In recent prison interviews, Rader told Osage County Sheriff Eddie Virden and other local area authorities he did not commit any other murders.

An attorney for the serial killer declined to comment to CNN.