IANAL but common sense is enough to see the dangers in hearsay evidence. And what was used in this case specifically was particularly risky because all the so called "independent" witnesses had seen all of the media circus and trial of Drew in the Media for 3 years.

The only reason they reopened the Savio case was that talking heads had convicted Drew of murder of Stacy, but had no evidence. The only reason they exhumed Kathleen's body is that they already had preconceived notions that they would find evidence of foul play.
To involve Baden in an autopsy was nuts since he of all people had preconceived ideas.. and had been making money off spouting his notions in the media for 3 years. It was he who pushed for the exhumation.. something of a media stunt. Even the legit autopsy is flawed from a scientific point of view.. because it was done with preconceived notions and expectations.