Those are some of the names we know. Unarmed, African-American men, shot dead by police officers. They are deaths that have made "Hands Up, Don't Shoot" an all-too-common refrain across the United States this past year.

And last month, Freddie Gray's name joined that list, in Baltimore.

But if you were listening to our documentary, "Screaming In The Dark" on yesterday's program, then you know there are also lesser-known names... such as Tyrone West. He also died in Baltimore... two years ago, after resisting arrest. His family is still fighting for accountability today.

All these cases have raised some troubling questions about just how often police kill people in the line of duty, and what it takes for those officers to face criminal charges. But the answers are surprisingly difficult to come by.

Philip Stinson is trying to change that. He's a former police officer who is now a criminologist at Bowling Green State University. He has compiled what many people believe is the most comprehensive data set about police shootings in the United States. Philip Stinson was in Perrysburg, Ohio.

This segment was produced by The Current's Gord Westmacott.