Zack Coughlan is accused of murdering Jamie Collins, who he studied with at the University of the West of England

A university student lay in wait for his housemate to return home before stabbing him 30 times, a murder trial has been told.

Zack Coughlan, 23, dressed in black and wore a mask and gloves to ambush Jamie Collins, 21, in the garden of their home near the University of West England in Bristol, where both were studying robotics.