A decorated Marine Corps staff sergeant from Virginia who apparently fatally shot his brother before killing himself at the end of a long police chase in Arizona had served four tours in Iraq.

His widow says he was suffering from post-traumatic stress disorder and recently had met President Bush.

Pinal County Sheriff's spokesman Mike Minter said no motive has been established for why 36-year-old Staff Sgt. Travis "T-Bo" Twiggs killed his 38-year-old brother Willard "Will" Twiggs and then himself Thursday.

Nor is it known why both brothers earlier in the week may have tried to commit suicide by attempting to drive their car into the Grand Canyon.

Kellee Twiggs of Stafford, Virginia says her husband Travis Twiggs began changing after his second tour of duty in Iraq and got worse after his third tour when he lost two very good friends from his platoon.

She said her husband was treated in the psychiatric ward of Bethesda Naval Medical Center and then sent to a Veterans Administration facility for four months. He worked with the Wounded Warrior Regiment and had accompanied a group to Washington a few weeks ago where he met President Bush at the White House.