Tragic link between slain policeman's wife and partner of man who would kill her husband.

The wife of slain Queensland police officer Brett Forte tried to protect the former partner of the violent criminal who would go on to kill her husband.

As a domestic violence liaison officer, Senior Constable Susan Forte worked to help the woman following a terrifying incident in March in which killer Rick Maddison pointed a gun at her while she held her young child in her arms, before firing in the air, The Courier-Mail reports.

After a 20 hour standoff, alleged cop killer Rick Maddison has been shot dead in the Lockyer Valley. #7News https://t.co/UqDkfveKXo pic.twitter.com/NGtoQBtLzC

— Samuel Hussey (@smhussey) May 30, 2017

In a cruel twist of fate, her husband Brett, also a senior constable, was in the process of trying to arrest Maddison for warrants linked to that incident and others, when he was shot dead in the Lockyer Valley last week.

Maddison was then shot dead following a lengthy police siege.

His ex’s link with Susan Forte was revealed on the day of her husband’s funeral.

“Susan was the domestic violence liaison officer. She supported me,” the woman, who wasn’t named, told the paper.

She said that after Maddison threatened her with the gun in March, she complained to police and went into a safe house.

The woman said she was devastated that Susan Forte had lost her husband, after working so hard to help her.

“She emailed me daily: ‘You will get there, you can do this, we will find him, don’t worry’. That is what broke my heart the most out of all of this. Out of all the people this could have happened to …” she told the paper.

The abuse she suffered at Maddison's hands was extreme. She says he once doused her in petrol and threatened to set her on fire. He would also show up at her house to menace her.

Thousands of mourners are expected at Snr Const Forte's funeral service in Toowoomba on Wednesday.

The 41-year-old husband and father of three young children will be farewelled with an honour guard by his police service colleagues.