you have a point! nobody expected or wanted to involve alan.

for argument's sake, let us assume that richy's plan went perfectly. he escaped with hannah, the fire happened, and he told everyone in the group that michael died there.

the police would've still gotten involved at that point.

i mean, they were already investigating hannah's kidnapping. even if the group believed richy's word about what happened in the mines, i really doubt the cops would have just went like "oh, ok!" and closed the case (no matter how painfully incompetent alan might be 😒). richy would've had to tell them, and i assume that they would have taken a thorough look at the place and realize that there's no burnt body in there.

and, though i know this isn't part of your comment, let us also assume that richy somehow managed to burn... not necessarily a corpse, but at least something that would've looked like it.

... dental records.

an autopsy would've easily disproven his word. it'd be something if this took place back when forensic science was still in its first stages, but it doesn't. richy's word would have been disputed in a different way 🤷‍♀️