JOINT BASE LEWIS-McCHORD, Wash. (AP) — Several government witnesses have testified that staff Sgt. Robert Bales was largely calm and cooperative when he turned himself in following a massacre at two Afghan villages in March.

But a soldier assigned to accompany him while he gathered his things also testified Tuesday that Bales smashed his laptop.

Sgt. Ross O'Rourke says he removed the laptop from Bales' rucksack after the defendant told him he didn't want to take it with him. O'Rourke says Bales then grabbed the computer and folded the screen back on itself, breaking it.

It was not clear if investigators recovered any evidence from the laptop.

One of Bales' colleagues testified Monday that he asked him to help bleach or dispose of his blood-soaked clothing following the massacre. Bales faces 16 counts of premeditated murder.