THE murder of a young schoolteacher has been solved thanks to a discarded cigarette butt that was found at the scene.

Rita Curran, 24, was found dead in her apartment in Burlington, Vermont, in July 1971.

Rita Curran was killed in Burlington, Vermont, in July 1971Credit: Burlington Police

At one point during their probe, detectives investigated if the case was linked to the notorious serial killer Ted BundyCredit: Getty

Cops have revealed that a cigarette butt helped investigators name William DeRoos as her killer – more than 50 years after Rita was murdered.

During their decades-long probe, officers investigated if her death was linked to the notorious serial killer Ted Bundy.

Investigators said he was born in Burlington, in the area where Rita was killed, and murdered young women and girls of a similar age.

Rita’s sister Mary Campbell sent the serial killer a letter asking if he murdered her sibling.

She said she received a reply from the FBI saying Bundy didn’t confirm or deny the killing.

The serial killer was ruled out as a suspect before he was executed.

More than 50 years later after Rita was murdered, cops believe DeRoos is responsible for the crime.

Burlington Police Detective Lieutenant James Trieb told reporters at a press conference: “We’re all confident that William DeRoos is responsible for the aggravated murder of Rita Curran, but because he died in a hotel room of a 𝒹𝓇𝓊𝑔 overdose, he will not be held accountable for his actions, but this case will be closed.”

Rita, a second-grade teacher, was found strangled, beaten, and sexually assaulted, the Burlington Free Press reported.

Cops revealed that DeRoos, then 31, lived just two floors above Rita.

They believe he killed Rita during a 70-minute window when he left his apartment.

DeRoos reportedly argued with his wife Michelle and told her that he went to “cool down,” according to police.

Investigators recovered several pieces of evidence, including a cigarette butt, from the crime scene.

Trieb revealed that it was found lying next to Rita’s arm.

He said: “It hadn’t been crushed or put out, it had been dropped there.”

In 2014, the cigarette butt was sent to labs in New York where it was forensically tested.

The DNA did not match the profile of the 13 people considered suspects, per the Free Press.

It hadn’t been crushed or put out, it had been dropped there

Burlington Police Detective Lt. James Trieb

Years later, law enforcement agencies partnered up with genealogy firms as they tried to link the stub to a suspect.

And, in 2022, Rita’s clothes were sent to a lab in Florida where they were examined.

Genealogy expert CeCe Moore was able to match the DNA found on the cigarette butt to DeRoos.

He said: “The DNA evidence ended up being so incredibly key and they couldn’t have possibly imagined the power that we would have at this time to actually use that to narrow it down to one person.”

Moore added: “This case was over 50 years old and it only took a few hours to narrow it down to William DeRoos.”

Cops revealed that DeRoos and his wife were quizzed the day after Rita was killed.

DeRoos told investigators that they had not seen or heard anything.

During the press conference, Trieb recalled: “Immediately upon closing the door, he turned to Michelle and told her that if the police ever showed up again, she was to tell him that he had been home all night.”

Michelle was quizzed by officers recently and seemed to change her account.

Jon Murad, the acting Burlington police chief, said: “Five decades later, she gave our detectives a different story: the truth.”

Thomas Chenette, a Burlington police detective corporal, revealed that he thinks Michelle changed her story because she was in love.

He added: “I think she lied at the time because she was young. She was naïve.”

DeRoos left the US and moved to Thailand where he became a monk.

He moved to San Francisco in 1974 where he met his second wife before he died in 1986.