Documents from a police investigation into the former University of Georgia professor who fatally shot his wife and two others show he had secretly recorded a conversation between he and his wife about her affair with one of the men killed.

In an application for a search warrant, Sgt. Christopher Nichols wrote that he thinks George Zinkhan was initially gathering evidence for a divorce from Marie Bruce.

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Click here for the 911 call transcripts.

Nichols adds that he thinks the marketing professor killed Bruce, Thomas Tanner and Ben Teague because of an affair between Bruce and Tanner.

Cadaver dogs found Zinkhan's body two weeks after the shootings in a shallow grave he dug for himself not far from his home in northern Georgia.

The documents were obtained by the Athens Banner-Herald.