Complex sentence: Serino said he felt pressured by several of his fellow police officers to press charges on Zimmerman when he believed there was not enough evidence to do so, and that one of the officers pressuring him was a friend of Martin's father.
Split into simpler sentences: Serino said he felt pressured by several of his fellow police officers to press charges against Zimmerman, although he believed there was not enough evidence to do so. One of the officers pressuring him was a friend of Martin's father.