For years, local television stations have aired surveillance videos of a suspect or a crime in progress with the “Crime Stoppers” stamp on it asking for the public’s help.

Last week, the Crime Stoppers tip line was a key component in finding Frank James, the suspect in the Sunset Park subway shooting.

Tips that went to the hotline also helped to catch the suspected serial killer who police say targeted homeless people in N.Y. and D.C.

But how does Crime Stoppers work behind the scenes? And where does that tip money come from?

President and CEO of the Police Foundation, Susan Birnbaum, and Sergeant Richard Wall from the NYPD Crime Stoppers Unit joined NY1 to answer those questions.

Crime Stoppers started in the 1980s. Since its inception, they’ve given out about $2 million in rewards.

The police foundation started 50 years ago. They fund programs that bring together police and the community, and programs that fight crime and terrorism.

The most important thing for people to know is that all calls are anonymous and translators are available as well.

Call 1-800-577-8477, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com, if you have a tip because those really make a difference.