Thousands of people sang with Prince at a concert for peace in the US city of Baltimore, in a response to the riots that followed the death in custody of young black man Freddie Gray, Efe news agency reported.
Prince returned to Baltimore on Sunday, 14 years since his last "Rally 4 Peace" concert there.
The concert, announced to everyone's surprise last week, offered a "catalyst for pause and reflection" after the incidents of April 27.
Among the audience was the Maryland State Prosecutor, Marilyn Mosby, whose office is responsible for Gray's case.
Shortly after his performance began, Prince invited her to the stage, where she made no statement, only greeting the public with a wave.
Mosby's spokesperson told the daily Baltimore Sun that the prosecutor was a big fan of the artist and that her tickets were a Mother's Day gift from husband Councillor Nick Mosby.
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Prince invited the prosecutor to join him for the performance of his new song "Baltimore", his tribute to black Americans who have died at the hands of police officers.
The song is available on the website SoundCloud.
"Does anyone hear us pray?/ For Michael Brown or Freddie Gray/ Peace is more than the absence of war," reads a verse of the song.
An undisclosed part of the fundraising concert, with tickets that cost between $22 and $497, will go to youth charities in the city.
The death of Freddie Gray led to the worst unrest in Baltimore for decades and once again highlighted the problem, also acknowledged by President Barack Obama, of mistrust between the police and minorities in the US.
The lawyers of the six officers charged with the death of Gray on Friday appealed either for the case to be dismissed or for Mosby to be removed from it over alleged conflict of interests.
Mosby has denied any conflict of interest and told CNN she would remain in charge of the case.
The Department of Justice also announced on Friday a federal investigation to determine if Baltimore police used abusive methods or discrimination in their activities.
Baltimore Mayor, Stephanie Rawlings-Blake, requested the investigation after the state prosecutor charged six officers involved in Gray's detention.