the very first interview he conducted with john ruetten suggests detective lyle mayer was already convincedt theory with john the night of the murder. narrator: remember, this is long before there was any talk of john's ex-girlfriend. there's a couple of possibilities here. matt mcgough, author of the book "the lazarus files," took a hard look at the investigation. he says there's no simple explanation for what went wrong. at one end of the spectrum is incompetence. and the other end of the spectrum is-- is willful cover-up. right? so it's somewhere along this spectrum. does that make sense to you that they would have started instantly covering up or deliberately looking away from somebody who they only knew as a fellow member of the department? ok. you just said covering up or deliberately looking away. covering up makes it sound like there's something active is required of those detectives to cover something up. a cover-up doesn't require anything active. a cover-up requires refusing to investigate what is obvious you have a responsibility to investigate. narrator: lyle mayer did not resp