"You have destroyed our lives with your stupid revenge"

A MOTHER who lost her son in a "senseless" revenge act against the 23-year-old's new girlfriend spoke of the heartbreak as his murderer was jailed for life.

Erika Varga, in her victim impact statement read to Brisbane Supreme Court, said Craig Anthony Leonard had created a hole in her family and deprived her of grandchildren when he did not even know her son, Nicholas Spohn.

"There is not a day that goes by that we don't miss him terribly," she said.

"You have destroyed our lives with your stupid revenge."

Leonard pleaded guilty on Tuesday to deliberately setting fire to the two-story timber home where his former girlfriend Rina Linda Mayall lived to scare and "put the wind up her".

He had told police he wanted to "take her down a peg" and "f*** her up financially" but he thought the fire would burn out in the room where he lit it.

The Caboolture 30-year-old also pleaded guilty to causing grievous bodily harm to Ms Mayall when she suffered severe smoke inhalation and fractured her back jumping from the second story to escape the fire.

He will serve life in jail, with a 20-year non-parole period, for killing Ms Mayall's new boyfriend of a few weeks, Mr Spohn, 23, and her aunt Jennifer Bachmann, 43, who did not escape the inferno.

Ms Mayall's six-year-old daughter was staying with her grandmother for the night.

Crown prosecutor Michael Byrne said Leonard had been in a relationship with Ms Mayall for seven or eight months but she ended it in January 2011.

He said they were still seeing each other until early April when Ms Mayall began dating Mr Spohn.

Mr Byrne said Ms Mayall had a party with family and friends on April 17, 2011, but had just gone to bed when she received a phone call from Leonard's friend.

That seems to have been the catalyst for Leonard collecting petrol from the Caboolture caravan park where he lived and setting a mattress in Ms Mayall's house on fire, before driving away so furiously that he crashed his car.

"To describe the prisoner's actions as merely being stupid and senseless would detract from the very high and inherent danger of what he did, resulting in the loss of the lives of two people he never met," Mr Byrne said.

"It does him no credit, though it may provide some explanation to say his actions were the product of an intoxicated mind, a mind that decided to exact a form of revenge on a former lover.

"It is fortunate there was not a third death. That is merely an accident as he did nothing to ensure that wasn't the result.

Defence barrister Robert East described the decision as "a fairly spontaneous event"

He said Leonard had been drinking all night, even refused service at one venue, and had taken methylamphetamines intravenously.

Mr East said Leonard was listening in on the phone call and learned Ms Mayall was in bed with her new boyfriend.

He said Ms Mayall asked whether Leonard was listening in and if he was to tell him he was a "wanker".

Leonard told the court he hoped the families he had hurt could have some closure now and could only imagine his actions had affected their lives.

"I know I am deserving of every ounce of their bitterness and anger," he said.

Leonard has already served 674 days behind bars.

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