Investigators said the bus driver, Su Ming-cheng, was depressed and drunk when he set fire to the vehicle, killing everybody on board.

"[Su], who was drunk driving, committed suicide by pouring gasoline and setting a fire, killing other passengers," local prosecutors said in a statement Saturday.

The depression was likely the result of a lawsuit over a fight with another tour guide and a separate lawsuit for sexual assault.

After having been suspended, Su was on his first day back on the job when he killed himself and 25 other people. Including the tour guide, 24 of the people were visiting Taiwan from China.

The safety exit on the bus was locked, trapping everyone inside.

Taiwanese authorities said Su was a heavy drinker with a history of violence.

The July 19 crash was the deadliest incident since Taiwan started allowing visitors from mainland China in 2008.

cw/cmk (AFP, AP)