Castle (2009)

S6E16 Room 147

A remorseful young woman admits to the murder of a down-on-his-luck actor, revealing specifics only the true murderer would know. Beckett and Castle initially believe they’ve solved the case, but soon discover evidence that clears their suspect. Just when things seem to settle, another individual steps forward, equally convinced of their guilt in the crime. This twist leads the team to realize that the truth behind the murder is much more complex than they initially believed.