Is it possible for back passenger side brake to lock up?

Involved in accident. Driver does not remember anything due to injuries. Crash investigator looked at van 1 1/2 months after accident. Said there was fluid and issues with the passenger side brake, he had to 'break' it free. Noticed a kink in tubing, BUT fluid had not bled out. There was only one skid mark (from the passenger location of van) Would there be more than one mark from other tires if breaks would be applied? Is it possible for the break to lock up? Would this cause the van to vear to the right out of control? What else should we look for? (We do know there was something going wrong with the van as the driver had asked friend to look at it-would have been day after accident)