VANCOUVER - A new trial has been ordered for a British Columbia man convicted of first-degree murder in the death of an 18-year-old girl on Halloween night in 2011.

A panel of B.C. Court of Appeal justices has unanimously agreed that two of five issues raised by for Mathew Foerster's lawyers are enough to require a second trial.

Foerster, who is now in his 30s, was convicted nearly three years ago in the killing of Taylor Van Diest, from Armstrong, B.C.

B.C.'s high court says the original jury should have been told Foerster's disposal of a shoelace and flashlight had no bearing on whether he was guilty of murder or manslaughter.

The Court of Appeal also says the jury was incorrectly instructed on how it could interpret Van Diest's last text message before her death, which said she was "being creeped" as she took a shortcut on her way to a Halloween event.

At trial, Foerster admitted he was responsible for the injuries to Van Diest, but contended he was only guilty of manslaughter or second-degree murder.