A Tasmanian man offered a fellow prisoner lucky Keno numbers as an incentive to kill his estranged wife, a jury has found.

Darryl Scott Donohue, previously of Invermay, has been found guilty of approaching two fellow inmates separately between May and June.

He offered one inmate cash and lucky Keno numbers to carry out the murder.

Donohue, 42, had pleaded not guilty to two counts of incitement to murder.

During the trial, an ex-inmate told the court he was offered $25,000 to "whack" Donohue's ex-wife and her parents.

He said he was given details about the woman's car, where she lived, where the children went to school and where her parents' lived, including a hand-drawn map.

Donohue denied having any conversations about poisoning his ex-wife and her parents with cyanide, or cutting their car brakes.

The former electrical tag tester also told the jury a sketch alleged to be a map of his ex-wife's parents' address was in fact a design for an LED light device.

He said a notebook contained phone numbers of fellow inmates with similar interests in fishing, not potential assassins.

He was previously jailed in February 2013 after he approached two men, including an undercover policeman, in 2012 and offered them money in exchange for killing his estranged wife.

Justice Robert Pearce has ordered a psychiatric report before sentencing, saying the approaches were bizarre and could point to a delusional condition.

Donohue is set to appear in court in February.