Sanford's Police Chief Cecil Smith is trying to heal a community

Jury selection has begun in the murder trial of a US neighbourhood watchman who killed an unarmed black teenager in a case that divided the US.

George Zimmerman, 29, says he shot 17-year-old Trayvon Martin in self-defence in Sanford, Florida, in February 2012.

Prosecutors say Mr Zimmerman, who is accused of second-degree murder, racially profiled the teenager, who was on his way home after buying sweets.

Mark Mardell reports.