(CBS News) SANFORD, Fla. - As many as 10,000 people, including Martin's parents, are expected to demand the arrest of George Zimmerman in the shooting of Trayvon Martin at a massive rally Thursday evening.
The unarmed 17-year-old was shot dead by Zimmerman, a neighborhood watch volunteer last month. Zimmerman has not been charged.
On Wednesday, Sanford's city commission voted no-confidence in police chief Bill Lee. His announcement Thursday that he would take a temporary leave, is the most visible step yet to defuse tension. CBS Correspondent Mark Strassman reports.
Video: Fla. Rep. may revisit "Stand Your Ground" law
"I do this in the hopes of restoring some semblance of calm to the city which has been in turmoil for several weeks," Lee said.
At the heart of the controversy is - did race play a role in the police investigation?
"When I check my heart, I have to say that I don't have confidence in the way it was handled," Sanford's Mayor Jeff Triplett said. "When I heard that Zimmerman was not arrested, I put my head in my hands."
A source close to the investigation tells that CBS police did not arrest Zimmerman because initial evidence supported his claim of self defense. For example, his face was bloodied and bruised.
CBS News has learned detectives interviewed Zimmerman for five hours the night of the shooting and again the following day at a re-enactment of the incident. They say he has been cooperative in the investigation.
Relations between Sanford police and its black community were strained well before Martin's shooting.
In 2010, a black homeless man was knocked unconscious as he tried to stop a fight. His white attacker, the son of a Sanford police lieutenant, wasn't charged for three weeks.
Mayor Triplett said Zimmerman should have been arrested.
When asked if he was satisfied with the investigation and if race was a factor in the case, Triplett said, "When there's strained trust, there's always that doubt, that conspiracy theory - was everything done that could have been done?"
Trayvon Martin's family met Thursday with U.S. Department of Justice officials looking into a possible hate crime.
They were told to be patient - a thorough investigation could take a while. The local grand jury will meet April 10.