An expert on excessive use of force by police will testify at the trial of Const. James Forcillo Wednesday.

Forcillo, 32, is facing charges of second-degree murder and attempted murder in the death of Sammy Yatim, 18, who was shot eight times on a streetcar just after midnight on July 26, 2013.

The jury has been told Robert Warshaw will offer his opinion on whether there were viable and reasonable alternatives to the shooting.

Warshaw served as chief of police in Rochester, N.Y., and Statesville, N.C., and was appointed by President Bill Clinton to serve as associate director of the Office of National Drug Control Policy in 1998.

Warshaw helped found Police Performance Solutions, a group which advises police departments on issues like race relations and the excessive use of force. He has been monitoring the Oakland Police Department for the last five years.