London Metropolitan Police concluded "it was just an accident", but they made sure to go to great lengths to "prove" he was a transvestite, homosexual and in to all sorts of freaky stuff. The family insisted he wasn't into any of that, but the police implied they'd find worse if the family didn't shut up. aka, "If you don't want us to make him a pedo as well, shut up."

https://theunredacted.com/gareth-williams-the-spy-in-the-bag/

Edit:

This from the article and they still kept trying to circle back to "it was an accident".

There was little or no DNA in the flat, which again is strange. The Police deny that the flat was forensically cleaned by persons unknown. Even Gareth’s fingerprints were nowhere to be found. He inexplicably would need to wipe any finger or palm prints from every surface in the bathroom before getting in the bag. Even if he was trying to get into the bag by himself, he would have needed to touch the side/bottom of the bath or the tiles at some point during the attempt. But nothing was found.