The eraser set . . .

It was a textbook case in 2017 of murder by overkill.

Here’s the newest chapter.

Sneed is told Wyndham Lathem, the brilliant ex-Northwestern University professor who is one of two men charged with the grisly River North murder of 26-year-old hairdresser Trenton Cornell-Duranleau, is now an armchair professor.

“My client, who is in a residential treatment unit at Cook County Jail, is not teaching in an official capacity — but helps explain basic biology, science and even politics to inmates in protective custody sitting around a deck table during their limited outdoor time one hour a day,” said Lathem’s attorney, Adam Sheppard.

“He’s a teacher. If they ask questions he answers,” said Sheppard — who claims his client, who reads a book every two days and is collecting them for a prison library, once tried to help organize a Christmas gift exchange among prisoners.

“And he is not the nutty professor,” added Sheppard.

“He is a brilliant microbiologist, who is now being treated for depression. Both his parents died during his incarceration. He continues to persist in his not guilty plea and that his co-defendant is literally to blame.”

Andrew Warren, Lathem’s English co-defendant — a former clerk at Oxford College — recently reached a plea agreement to cooperate with Cook County prosecutors. It stipulates Warren would be sentenced to 45 years in exchange for his cooperation.

Both men were charged in August 2017 with the murder of Cornell-Duranleau, who was found stabbed nearly 70 times and almost decapitated on July 27 inside Lathem’s River North apartment.

Lathem reportedly sent video messages to friends and family while he and Warren were on the run, in which Lathem expressed remorse for betraying Cornell-Duranleau’s trust and making “the biggest mistake of my life.”

Lathem also dropped Warren off at a police station near Golden Gate Park, then drove himself to Oakland and turned himself in to police there. Both men have been held without bond since their arrest.

“My client is remaining hopeful. His friends are remaining steadfast and visiting. Although no date has been set for his trial, I expect it to be in the next three months,” said Sheppard.