The chief suspect in the deadly murder of a Louth mum, had tried to attack a priest in recent weeks, it has emerged.

The Evening Herald reports the man being questioned over the brutal murder of 34-year-old Jacqueline McDonagh, has a history of violence.

McDonagh, who had starred in the move “Knuckle” alongside her husband, Michael Quinn McDonagh, was beaten to death at her family home in Dundalk in the early hours of Wednesday morning. The first scene in the internationally acclaimed movie is from the couple's wedding in 1997.

According to reports, the couple’s three children Chloe, 14, Nikita, 10, and Mikey, 5, were all in the house at the time of the murder.

Investigators are now focused on a suspect in his twenties, whom was known to the victim.

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"This man's behaviour in recent times has been particularly erratic -- he even attempted to attack a priest," a source revealed.

“He has been heavily involved in a Traveller feud in Finglas that has been going on for well over a year at this stage – in fact he is one of the main instigators.

“This feud has seen lots of serious criminality including pipe bomb attacks, assaults and damage to property.

“The fact is that this man needed help from the health services a long time ago. It is no exaggeration to describe him as a psychopath – a real danger to those around him.”

On Thursday, investigators questioned Michael Quinn McDonagh at Store Street Garda Station in Dublin. Police have yet to make any arrests.

The victim's eldest brother John, 42, paid tribute to his “fantastic sister."

He told the Irish Sun: “We expect our beautiful sister to be returned to us sometime next week.

“She was a fantastic sister, mother, daughter and friend to everyone who knew her.

“We’re just devastated at the moment and we can’t believe our beautiful sister is gone.

“I don’t think we’ll ever get over losing someone as special as her.”