BELLINGHAM, Wash. — Closing arguments concluded Wednesday in the cold case murder trial of 18-year-old Mandy Stavik.

Stavik's neighbor, Timothy Bass, is accused of raping and murdering Stavik in 1989 before dumping her body in the Nooksack River. His fate is now in the hands of a Whatcom County jury.

Stavik disappeared after going out for a jog the day after Thanksgiving in 1989. Her naked body was found in the Nooksack River three days after she disappeared. DNA collected from a Coke can at Bass’ workplace led to his arrest in late 2017.

The jury must decide if the DNA, along with other circumstantial evidence, is enough to send Bass to prison for the rest of his life.

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Special Prosecutor Dave McEachran came out of retirement to try the case.

"This was an atrocious thing," McEachran said to the jury. "I ask you to hold him accountable. I ask you to find him guilty of murder in the first degree."

McEachran pointed to a pattern of apparent lies Bass told the police.

Bass told police he didn't really know Stavik. However, when he was confronted with the DNA evidence he said they had consensual sex just before someone else killed her. Bass also asked his mother to concoct a fake alibi.

"He asked his brother to make up a story that he had sex with her. He asked his mother if they could blame it on his deceased father. Why would he do this? I ask you to use your common sense," McEachran implored.

The chances of the DNA found inside Stavik belonging to someone else are 1 in 11 quadrillion. That's more than the number of people on the planet. To prosecutors, it was their smoking gun.

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"You'd have to be an extraterrestrial in order for this to not be you," the veteran prosecutor said.

"The science tells a different story," Defense Attorney Shoshana Paige said.

Bass' attorneys argued investigators jumped to the conclusion that Stavik had been raped back in 1989, but that may not be the case. 

Forensic experts testified that it's entirely possible Bass did have consensual sex with Stavik up to 12 hours before her death.

And that does not mean he killed her.

"There's no DNA of Mr. Bass under her fingernails," said Paige. "There's no physical evidence that puts him anywhere near the river."

Detectives interviewed three other potential suspects at the time, but they were never arrested because their DNA was not a match.

"Which begs the question, did law enforcement commit a fundamental error in assuming she had been raped," posited Defense Attorney Starck Follis

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As for Bass asking his mother to help construct an alibi, Follis offered an explanation.

"With the jaws of justice coming down on you, is it unreasonable to say I need to put an alibi together? I need to figure out where I was on that date in order to prove I didn't do this?" Follis asked.

Follis finished by saying the case is simply, "a question mark, a mystery."

McEachran urged jurors not to be misled and to use their common sense.

Deliberations begin Thursday morning.