Alaskan serial killer Israel Keyes allegedly broke his own rule, and that led to his capture, ABC News reported.

Because of his mistake, his careful years of calculated killings for seemingly no other motive than thrills were brought to an abrupt end when he was placed behind bars.

ABC News explained that when the 34-year-old man approached a coffee stand in Anchorage on Feb. 1, if he had followed his usual modus operandi, he would have only robbed the place and left.

However, Keyes couldn’t help himself, he told authorities, when he walked inside and saw teenage barista Samantha Koeing all by herself.

He first was going to target her boyfriend, Fox News revealed, but then changed his mind to the young barista.

Keyes dragged the teenager out of the store and then proceeded to bring her into his own car, where he raped her and strangled her. He was ultimately arrested for her murder.

"In prior cases, he had enough self-control to walk away from it, to not commit the kidnapping, to not commit the abduction and with Samantha he didn't," Anchorage homicide Detective Monique Doll told ABC Monday. "He broke his own rule. He had drawn his line in the sand and he couldn't help himself, he said. He took her anyway."

When Keyes was arrested on March 12, it marked the end to a decade of hunting and murdering victims.

He would plan for his future crimes by burying murder kits of weapons, cash and tools to dispose of bodies. 

But Keyes' explanation of his methods to authorities abruptly ended when he committed suicide in his jail cell on Dec. 1.

Since his death authorities are trying to fill in the blanks to the way Keyes lived his vicious life. They believe he murdered anywhere from eight to 12 people including Koeing, but only three victims have definitively been tied to the Alaskan serial killer.

Before the jail cell suicide, Keyes was explaining how he remained under the radar for so long.

"He basically had this rule, this unwritten rule, that he would travel outside and go to great lengths to distance himself from any of his victims," Doll said. "He told us he was losing control. He was losing the massive amount of self-control that he had."

Koeing’s murder broke two rules: She didn’t have her own car and she was from Anchorage like Keyes.

"Mr. Keyes told us that he was deciding as he walked up the coffee kiosk that if the person working inside did not have a vehicle he was only going to rob the [place] and walk away because he did not want to transport his victim in his vehicle," Doll said.

Even though Keyes knew Koeing didn’t have a car after seeing her, he couldn’t suppress his desire to kill.

After speaking to police for nearly 40 hours, he divulged how he killed animals as a child and planned on taking his own life before he was captured by authorities.

"He didn't plan on being taken alive," Anchorage Police Officer Jeff Bell said at the news conference.

Though Keyes researched other serial killers, he didn’t want to be referred to as one.

"He had researched and read other serial killers. He knew a lot about Ted Bundy," Doll said. "He was very careful to say that he had not patterned himself after any other serial killers, that his ideas were his own. He was very clear about that distinction. That mattered a lot to him."

"He never identified himself as a serial killer," she said. "That was one of the things that he wanted very much, as this investigation progressed, to keep from being identified as."

The FBI wants anyone who has information about Keyes contact the FBI at 1-800-CALL-FBI.