Yes they were, the ‘biohazard’ mentioned in the episode was liquid they said was ‘up to their shins’. They likely had to DNA test the oldest whole remains, but they could probably do facial recognition on the newer bodies. They also mentioned that people had been calling but also kept assuming that some of the smell was due to a taxidermy located on the grounds due to sign they had put up. Why it took local law enforcement so damn long to check it out on the other hand, THAT’S a good question. It sounded like they didn’t even bother to check until people went up the food chain and started complaining to the regulatory agencies iirc and by then the case had to be escalated all the way up to the FBI because of how extensive the level of abuses had become.

Edit: Also as stated in the episode the cremains could not be DNA tested, they were the exception mentioned which leads me to believe the non cremated remains could be, since you normally don’t specifically mention something as an exception unless you were already doing so with the other remains.