In pictures: Trayvon Martin protests

A demonstration in Washington against the verdict handed down to George Zimmerman over the death of black teenager Trayvon Martin, 20 July 2013

Demonstrations have been taking place across the US against the verdict of not guilty handed down to Florida volunteer night watchman George Zimmerman last Saturday.

Trayvon Martins mother Sybrina Fulton speaks at a podium as Trayvon Martins brother Jahvaris Fulton (l) stands by during a rally honouring Trayvon Martin organized by the National Action Network outside One Police Plaza in Manhattan 20 July 2013 in New York City.

Mr Zimmerman was found not guilty of charges of second degree murder and manslaughter after shooting dead unarmed black teenager Trayvon Martin. Trayvon's mother Sybrina Fulton and his brother Jahvaris Fulton attended one of the protests in Manhattan.

Singer Beyonce and husband Jay Z at the New York rally a week after the verdict of not guilty handed down to George Zimmerman over the death of black teenager Trayvon Martin, 20 July 2013

Singer Beyonce and husband Jay Z were among several celebrities to speak out against the verdict. This rally, in New York, was also attended by organiser and rights activist, the Reverend Al Sharpton.

A demonstration in Washington against the verdict handed down to George Zimmerman over the death of black teenager Trayvon Martin, 20 July 2013

Protesters want to see federal charges brought against George Zimmerman, who was acquitted by a Florida court.

Tracy Martin, father of Trayvon Martin, stands next to his nephew Stephen Martin (r) during a rally for his son in Miami 20 July 2013

Trayvon Martin's father, Tracy, along with nephew Stephen Martin were at the Miami rally as the crowd sang the rights anthem We Shall Overcome.

People attend a rally led by Tracy Martin, father of Trayvon Martin, in Miami 20 July 2013

The demonstrators are angered, too, by Florida's "stand your ground" law allowing the use of lethal force if a citizen fears for his or her life. Critics say it encourages a "shoot first" attitude.

President Obama commenting on the Trayvon Martin killing, 19 July 2013

President Obama, commenting on Friday for the first time after the verdict, said: "When Trayvon Martin was first shot, I said that this could have been my son. Another way of saying that is Trayvon Martin could have been me, 35 years ago."