Patrolman Brian Johnson of the Franklin, Mass., Police Department studied a surveillance video showing two men using allegedly stolen credit cards at a Home Depot.

But when Johnson didn’t recognize either man, he decided to involve people — a lot of them — to help crack the case. He posted a clip from a security camera on, Google Inc.’s video-sharing Web site, then e-mailed the clip’s link to about 300 people and organizations saying the department was looking for the men.