Complex sentence: Merah exchanged a Colt.45 for a walkie-talkie, which was used to communicate with the police and tell them the location of a bag containing the blood-spattered camera used to film his attacks.
Split into simpler sentences: Merah exchanged a Colt.45 for a walkie-talkie which was used to communicate with the police. He told them the location of a bag containing the blood-spattered camera that he had used to film his attacks.