The FBI does get DNA from the bench, from five different people, and a cat. The college asks the student body to volunteer for DNA testing, with a concession to privacy, that if there is no match, the DNA sample will be discarded. Refusal to cooperate will be grounds for arrest by the FBI, followed by mandatory DNA testing. 

For the first time Ted is worried. He knows that a match doesn’t prove anything, except that he sat on the bench, but it would bring a level of scrutiny that might further implicate him:

a search of his apartment, sales records on ammo and other supplies. 

He decides to go do the test. He can always shoot himself at the last minute. First he stashes the Walther in his locker. When he gets to the testing room, it’s Special Agent Coluvis that takes his sample.  

Ted thinks of trying to cover himself by mentioning that he uses that bench to read occasionally… that bench? Was it mentioned specifically in the paper, or on the TV news? He can’t remember and decides on silence. 

Coluvis has what is probably a telepathic insight into other people, and was certain that Ted was the Reaper from the minute he met him, but he also agrees perfectly with what Valdison said in his address, and for this reason, discards Ted’s sample, replacing it with another that he gets on the way to the lab. 

Ted drives home fast, puts all his arsenal items nearby in a small storage unit that he rents under a false name. This is a good idea anyway, and he should have thought of it sooner as a general precaution. 

He is, nonetheless, on pins and needles for the next three days. Finally, he reasons that he probably didn’t leave any DNA behind on the bench. A light breeze could blow away a hair, lint from clothing is not specific to him, etc.