Launceston man promised to 'f--k up' woman before alleged double murder, court hears

A Launceston man accused of a double murder texted a friend he was going to "f--- up" one of the alleged victims four days before she died, a court has heard.

Marco Daniel Rusterholz has pleaded not guilty to the August 2012 murders of Angela Maree Hallam and Joshua Eric Newman in Ravenswood, The Mercury reports.

Crown prosecutor John Ransom showed Launceston Supreme Court a text message sent on August 11, four days before the alleged killings, from Mr Rusterholz to an unnamed friend.

"Good one mate, now let’s f--- that Hallam up," the text said.

"Yes that is the main event. Let’s unleash hell," the friend replied.

"Ha ha glorious hell," Mr Rusterholz then said.

Prosecutors also showed the court a text sent by Mr Rusterholz on August 15, the day of the alleged killings, to his then-girlfriend Sally Maher.

"Are you going to be home soon?... I’ve got a birthday present for you," the text said.

Prosecutors allege Mr Rusterholz cut a lock of Ms Hallam’s hair to take to Hobart for Ms Maher.

The court heard Mr Rusterholz and Ms Hallam were in frequent contact in the hours leading up to her death.

The trial continues.