Richard, there's been no statement of responsibility from the person in custody or anybody claiming to speak for him.

There are photos of him (his face was matched to his passport photo by facial recognition) entering the incident zone with a large dark backpack and leaving without the backpack.

News reports (for what it's worth) that they told the victim of carjacking prior to the manhunt, "We just killed a cop and bombed the race. Get into the car." He did, and was released after withdrawing as much cash from ATMs as was possible.

During the chase, pipe bombs and a defective pressure cooker bomb were thrown. (The pressure cooker bomb exploded but the cover had loosened, making it ineffective).

Certainly, there will be formal interrogation. There have been numerous reports from other places that computers have been confiscated, ordinance rendered safe, and people detained (though I don't think there have been any other arrests). It will probably be a long time before any completely coherent story emerges, but I'm pretty satisfied that they have the right person and there are no others immediately involved. But of course, he is still officially the alleged bomber.