Why police believe serial killer BTK could be behind two unsolved cases

Why police believe serial killer BTK could be behind two unsolved cases

Dennis Rader, the infamous serial killer known as BTK, who inspired both Stephen King and the Netflix series Mindhunter, has been named a "prime suspect" in at least two additional unsolved murders.

Osage County police say they believe Rader is linked to the disappearance and murder of two women between the 1970s and 1990s.

The new leads saw authorities dig near the killer's former Kansas property, finding "items of interest" this week. 

Here's what we know about BTK and why police believe he could be responsible for the cold cases.

Who is the BTK killer? 

Rader, a former Kansas city code inspector, killed 10 people between 1974 and 1991, and notoriously gave himself the nickname BTK, standing for "bind, torture, kill".

He often sent taunting letters to police and media, claiming responsibility for his sexually-twisted trail of crime in the Wichita area. 

He was arrested in February 2005, after revealing key evidence to media following years of silence.

His letter to newspaper The Wichita Eagle included photos of a 1986 strangling victim and a photocopy of her missing driver's licence.

That letter was followed by several other cryptic messages and packages.

The break in the case came after a computer diskette Rader sent was traced to the church, where he once served as president.

He was sentenced in August 2005 to 10 consecutive life prison terms.

The nature of his murders inspired several documentaries and author Stephen King said his book A Good Marriage was based on the killer.

TV crime show Mindhunter also used details from Rader's story in season two of the Netflix series. 

Families of Dennis Rader's victims said he "does not deserve to live" following his sentence. (Reuters: Wichita Eagle/Bo Rader/Pool)

The new lead in the disappearance of Cynthia Kinney

Cynthia Kinney was a 16-year-old cheerleader in Pawhuska, Oklahoma, who went missing in 1976.

She was last seen at the Osage Laundromat her aunt and uncle owned.

Some witnesses reported seeing Ms Kinney get into a faded beige 1965 Plymouth Belvedere with two people. 

After her disappearance, there were several reported sightings but authorities were never able to find the teen. 

However, the case, which was investigated on and off over the years, was reopened in December last year. 

Osage County Sheriff Eddie Virden told KAKE-TV a bank was having new ADT alarms installed across the street from the laundromat when Ms Kinney went missing. 

Rader was a regional installer for ADT at the time, although the sheriff was not able to confirm that Rader installed the systems.

Sheriff Virden said he decided to investigate when he learned that Rader had included the phrase "bad laundry day" in his writings.

Osage County Undersheriff Gary Upton said the investigation "spiralled out from there" into other unsolved murders and missing persons cases.

Cynthia Kinney went missing from the Osage Laundromat in 1967.(Supplied: National Missing and Unidentified Persons System)

"We sit just on the other side of the state line from Kansas and Wichita, which is his stomping grounds," he said.

"We were following leads based off of our investigations and just unpacked other missing persons and murders, unsolved homicides that possibly point towards BTK." 

The murder of Shawna Beth Garber

Rader is also now the prime suspect in the death of 22-year-old Shawna Beth Garber.

Ms Garber's body was discovered in December 1990 in McDonald County, Missouri.

An autopsy revealed she had been raped, strangled and restrained with different bindings about two months before her body was found.

Shawna Beth Garber's death matches some of Dennis Rader's previous murders. (AP Photo: Travis Heying/The Wichita Eagle )

Her remains were not identified until 2021. 

Until then, she was known as Grace Doe because police said "only by the grace of God" would anyone find out who she was.

But McDonald County Sheriff Rob Evenson told KSNF-TV and KODE-TV, Rader has denied any involvement in Ms Garber's death.

Sheriff Evenson said they have "worked with the Oklahoma investigators in the past, but so far, there has been no direct evidence linking Rader to the case".

'Items of interest' found in dig

Little information has been released yet about what the search on Tuesday in Park City, Kansas uncovered.

Undersheriff Upton described the discoveries only as "items of interest," in a news release.

The release said the items would undergo a thorough examination to determine their potential relevance.

Sheriff Virden told KAKE-TV some items were deeply buried.

Dirt and rebar litter the ground following a police search of Dennis Rader's former Park City home.(AP Photo: Eduardo Castillo/The Wichita Eagle )

He also said that some items were found during a previous excavation of the property in April, including a piece of aged, ripped panty hose.

"It was very, very clear someone had created this hole and refilled it with a different material. Took some precaution to kind of protect some of those items," Sheriff Virden said.

Undersheriff Upton said his department is working with the Kansas Bureau of Investigation.

He declined to say how many other missing person and homicide cases are being re-examined, but told the Associated Press Rader could be a suspect in more cases.

Rader's daughter Kerri Rawson told Fox News that she believes investigators were looking for items Rader may have kept and buried on his property under a metal shed he built.

Ms Rawson said she also told investigators to check where Rader buried the family dog.

"I'm still not 100 per cent sure my dad did commit any more at this point," she told the The Wichita Eagle. 

 "If my dad has harmed somebody else, we need answers."