CHICAGO (CBS/AP) — Former Northwestern University professor Wyndham Lathem has been convicted in the 2017 stabbing death of his boyfriend, Trenton James Cornell-Duranleau, in what prosecutors described as a thrill killing.

A Cook County jury found Lathem, 47, guilty of first-degree murder on Thursday, following a week of testimony.

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He faces a sentence of 20 to 60 years in prison.

Cornell-Duranleau’s slaying was part of what prosecutors said was a sexual fantasy he shared with another man who was charged in the case.

Lathem was accused of stabbing Cornell-Duranleau – a 26-year-old hair stylist from Michigan – dozens of times in Lathem’s Chicago high-rise condominium.

Andrew Warren and Wyndham Lathem.

Lathem, a renowned microbiologist, and Andrew Warren, an Oxford University financial officer, were arrested in California after an eight-day manhunt following Cornell-Duranleau’s death. Warren pleaded guilty in 2019.

During his trial, Lathem took the stand to contend Warren committed the crime while he cowered in a nearby bathroom.

A day after he pinned the blame on Warren, who has pleaded guilty to murder for his role in the slaying, Lathem under questioning from the prosecutor acknowledged that not only did he not try to stop Warren from killing his boyfriend, but he took a shower before the two fled together.

From the witness stand, Lathem, a renowned microbiologist, said he was in shock and believed the authorities would blame him for the killing of Cornell-Duranleau, who was stabbed dozens of times in Lathem’s Chicago apartment. But he acknowledged that he had ample opportunity to tell someone what happened,, starting with the doorman at his apartment building.

“(You) didn’t tell the door man (that) this man from England just butchered my boyfriend did you?” Assistant State’s Attorney Craig Engebretson asked.

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“No,” Lathem said.

Nor, he said, did he tell any of the several people he crossed paths with after he and Warren fled Chicago before the two were were arrested eight days later in Northern California after leading authorities on a national manhunt.

On Tuesday, Lathem testified that Warren alone stabbed Cornell-Duranleau during what started as a mathemphatime-fueled sexual encounter involving the three men.

Trenton James Cornell-Duranleau (Family Photo)

“I didn’t stop Andrew from hurting him, I didn’t,” Lathem testified. “I hid in the bathroom like a coward.”

That contradicted the testimony earlier in the trial by Warren, who in 2019 pleaded guilty to first-degree murder as part of a plea agreement that called for him to testify against Lathem in exchange for receiving a 45-year prison sentence.

Warren, who was an Oxford University financial officer at the time of the slaying, testified that he flew from England to Chicago to meet Lathem and take part in a pact to kill each other before agreeing to kill the 26-year-old Cornell-Duranleau at Lathem’s suggestion.

He testified that he did, in fact, stab Cornell-Duranleau, but only after Lathem had already begun stabbing him.

Lathem’s testimony also contradicted what he said on a video that was linked to an email he sent his parents days after the slaying.

“He trusted me completely and felt safe with me, and I betrayed that,” Lathem said on the video that the parents turned over to the U.S. Marshal’s Service and played for the jury by prosecutors last week and again on Wednesday. “I took that all away when I killed him.”

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(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

CBS 2 Chicago Staff