Lambart ran her over, then told Sam to go away and do some dangerous stuff so he wouldnt have time to investigate. Then Lambart started thinking about what Sam might do to him if he finds out, so he got him self captured then in the uncut version of DA shouted things like "haha Sam I can see my reflection on that bald chrome of urs", so Sam shot him
I think it's quite obvious that Sam is actually traveling back in time in Conviction to stop the murder of his daughter. Unfortunately, due to the stress of this responsibility, he stops into a bar that very night and has a few drinks...his driving skills later on would be suspect at best...the game ends with him behind the wheel saying "Did I just hit a dear? Oh well, off to save Sarah."