A man facing a possible five-year prison sentence went on trial Tuesday for allegedly causing a fatal accident after winning more than 500,000 euros ($537,000) gambling and then going on a 36-hour alcohol- and cocaine-fueled binge.

The 51-year-old man, identified only as Marko M. in line with German privacy laws, faces one count of negligent homicide and six counts of causing bodily harm in collisions while he was driving the wrong way on an Autobahn.

He cried as he gave his opening statement, telling survivors of the 2011 crash and their relatives he was "unbelievably sorry," the dpa news agency reported.

"I still don't understand it to this day," he said. "I've been asking myself about it every day for three years. I hate myself for it."

After hitting the jackpot in a Wiesbaden casino, the man admitted to authorities he went on a 36-hour partying binge with friends and relatives in several cities -- including a stop in Bad Homburg where he won another 20,000 euros ($21,500), prosecutors' spokesman Andreas Winckelmann told The Associated Press.

"During this whole time he was always partying, drinking and doing drugs," Winckelmann said.

Pleas are not entered in the German system, but a court expert has said the man was so intoxicated that he can't be held entirely responsible for his actions, Winckelmann said.

The suspect eventually ended up on the Autobahn in his Volkswagen Touareg SUV going the wrong way. His head-on crash with another car  killed a man and seriously injured the man's wife and son, Winckelmann said.

He then drove another yards and collided with another car, injuring both occupants. Two other people were injured when they were unable to stop in time and slammed into the accident scene.

Winckelmann said the suspect then fled on foot with his winnings, walking some 25 miles into Frankfurt where he slept overnight at a friend's house before turning himself in to police the next day.