From missing persons cases to some of the city's most wanted suspects, police sketches are often a crucial tool in helping the NYPD crack cases. But what goes into creating the drawings?

News 12 visited NYPD Headquarters to catch up with sketch artist Detective Jason Harvey, who helps solve cases with pencils and his pad.

Harvey started out as a patrol officer in the 32nd Precinct in Harlem. His skills and personality brought him to the artist unit 10 years ago.

To create a sketch, Harvey says a case detective will first bring in a victim or witness for an interview. The person is shown pictures of faces to get a general starting point by picking out features from the photographs, such as the shape of the eyes, the nose and the mouth.

"This is something that is tried and true," Harvey says. "It's the best medium to use when you're working with memory."

With all of the technology available to law enforcement, such as facial recognition software, the sketch drawings are often a huge help in tracking down suspects. A recent success story involving a suspect sketch involved the stabbing of two young children in East New York. The suspect was arrested after a sketch was released.

Still, it's not a perfect science. While the sketch in the stabbing case resembled the accused killer, other times, the sketches may not. "We're only as good at the witness' or victim's memory," Harvey says.

A resemblance to a sketch doesn't guarantee a conviction. "Once you've identified the person, you still have to establish probable cause, [which] can't be established through a sketch," Harvey adds.