Danielle Geier, 32, and George Ishler, 39, thought they both featured in Ronald Bettig’s last will and testament.
According to the New York Daily News, cops found the body of the media studies teacher in a quarry in Centre County, Pennsylvania, US, on Wednesday.
The 56-year-old, who taught at Pennsylvania State University and was referred to as "the nutty professor" by those who didn't know him, and was friends with the pair.
Geier and Ishler were "known drug users" according to police. They are accused of killing Bettig for the benefits, and authorities said Geier was sharing his home, according to the Centre Daily Times.
In court documents it stated the pair had originally plotted to have Ishler drown Bettig when they went to Rehoboth Beach in Delaware.
They later decided it another option was to kill him at the Centre County quarry.
A text which Geier sent while on the ocean trip read: "So ready I am pissed off."
Police interpreted this to mean she was ready to kill Bettig because he had commented on the way her son was being raised.
The pair convinced Bettig to travel to the quarry because they said they could harvest marijuana there, then allegedly pushed him to his death.
Geier confessed to police they staged it to make it look like the professor was there alone, putting his bottles, flashlight, hand rake and a bag near the quarry.
They then reported him missing three days later.
He was last seen on August 12 and they reported him missing on August 15.
Their plot was revealed when there were inconsistencies in their story - court documents said they told cops Bettig may have travelled to California.
Dean Marie Hardin, of the College of Communications at Pennsylvania State University, said: "We are deeply saddened by the loss.
"He was a part of the fabric of this College for many years.
'All except our very newest faculty and staff members very likely knew Ron, who was one of our longest-tenured faculty members.
"Ron was the kind of teacher who connected powerfully with students, who found his classes in political economy - at both the undergraduate and graduate levels - transformative."