EUGENE — A former inmate has pleaded guilty to conspiring to threaten a prospective witness against a man who has been jailed on charges of identity theft and fraud in a scheme to fake his own death.

The plea Tuesday from Robert Joseph Landreth was the latest turn in a fraud case involving Randy Arlen Mainwaring, 41, who was once the manager of a local bank office.

Landreth and Mainwaring were in the same Lane County jail dormitory in October 2010 when the witness was threatened during a call that was placed four hours after Landreth’s release, according to an FBI affidavit.

‘We’re gonna take you all out’

Landreth told Judge Michael Hogan that he called the woman on Mainwaring’s behalf, the Register-Guard reported. He said he left a voicemail threatening her and her parents.

In the obscenity-laden message, Landreth told the woman that she had messed with the wrong person, and that if she continued to do so, “we’re gonna take you all out.”

Mainwaring has not been charged in connection with that call.

Agent Timothy Suttles said in the affidavit that Mainwaring used jail phones to call the woman more than 300 times in August 2010. When the woman stopped answering and informed the FBI, he began calling her parents, Suttles said.

Mainwaring was indicted in 2009 on charges of aggravated identity theft and bank and computer fraud, two years after his former employer filed a lawsuit claiming he planned to use a customer’s information as part of a scheme to fake his death and then use the customer’s identity.

He had been convicted of arson in Florida for trying to burn down the house of his estranged wife and of trying to frame her by planting drugs in her car. The arson conviction was overturned on grounds he didn’t get a speedy trial.

Phony obituary

Two months after the bank lawsuit, Mainwaring pretended to be his brother when he submitted a phony obituary for himself to The Eugene Register-Guard, which published it based on what turned out to be a bogus copy of a United Kingdom death certificate.

A sister and Mainwaring have told the paper he has bipolar disorder.

Landreth’s sentencing was scheduled for November. Both the defense and prosecution referred to a plea deal, but the judge sealed the document.