OSAGE COUNTY, Okla. (KSNW) — The Osage County, Oklahoma, undersheriff says they have at least four “pretty strong connections” to cold case investigations linked to Dennis Rader, BTK, they feel could go to trial.

On Tuesday, the undersheriff said they have been following leads from several cold cases they feel could be linked to Rader.

Undersheriff Gary Upton says they are looking to connect with the Wichita Police Department to look at evidence WPD has that could connect Rader to their investigations.

Upton says items of interest include a green dress and a red blanket.

He says the leads they are looking into are not specifically tied to Cynthia Dawn Kinney, missing out of Oklahoma. However, they still consider Rader a “prime suspect” in her disappearance.

In April, the Osage County Sheriff’s Office searched Rader’s former property in Park City and found a pantyhose ligature they believe Rader used to tie up victims. Upton says it has not been sent for DNA testing, but they plan to do that.

Rader, 78, has been in the El Dorado Correctional Facility since his sentencing in 2005.