Officials had been planning the sting since April, when a Merced police officer was gunned down, allegedly by a gang member. This past Sunday officers from nine local and state law enforcement agencies carried out the operation. Some 50 arrests were made on a wide range of charges including parole violation, and drug possession. Sheriff Mark Pazin says executing the sting on a Sunday caught the gangs by surprise.   PAZIN :13—We got a number of fresh charges on some of the other persons we put in jail. We scored a number of vehicles so all in all I think it was a huge success and we’re going to use this as a template for the future.   For obvious reasons Pazin declined to discuss details of future stings, but he said knowing they could occur at any time will keep gangs off balance. A spokeswoman says the District Attorney’s office hadn’t received police reports on the arrests, so she couldn’t comment on the prosecutions. Bob Hensley KXJZ News.