[Cecily]

Other law enforcement people involved in the case supported Steve Thomas, and they didn't write any books. What was their motive for agreeing with him?

[MizSterious]

According to what I've read, the "other law enforcement" probably agreed because they were determined that one of the parents, probably (according to them) Patsy, did it. Tunnel vision.

[Orange1998]

Steve Thomas was a convincing guy. Means nothing in the rule of law. Maybe you should ask the perp the motive.

[1L]

>>What was their motive for agreeing with him?<<

Idiocy, and/or thinking that if the police believe its likely, it must be true.