Lee Jr., the case's lead detective, Investigator Chris Serino, and other department managers sat down for an exclusive interview with the Orlando Sentinel today.
They have worked closely with prosecutors, Serino said, and have not arrested Zimmerman because prosecutors have consistently told them they do not have enough evidence to win a manslaughter conviction.
That's because Zimmerman says he was defending himself, something he's allowed to do under Florida law.
The best account of what happened came from Zimmerman, Serino said. Other witnesses who saw or heard parts of what happened corroborate his version of events, the investigator said.
Zimmerman told police he got out of his SUV to follow Trayvon on foot, and the 17-year-old came toward him.
The two got into a fight, and Zimmerman wound up on the ground, he told police. Trayvon hit him in the face, and Zimmerman yelled for help.
Several witnesses heard the fight, including a 13-year-old boy out walking his dog, but there have been different accounts of who was crying for help.
It was Zimmerman, Serino said. He said he is certain of that because he played a recording of that voice for Trayvon's father, Tracy Martin, and the Miami man said the voice was not his son's.