Something must have gone wrong. He survived. Sources say that there were explosives in the truck so he might have had other plans.
The police published the pictures short after the attack causing people to recognize him as he entered a train and went home. Publishing the picture caused the quick arrest.
The guy is a Uzbek citizen and allegedly a person of interest to Russia. He is affiliated with Hizb-ut-Tahrir a pan-islamic political organization. He’s also said to be one of Daesh followers.
He seem to have five kids and a normal family life on the side.