For many police officers and Fond du Lac residents it may seem hard to believe that four years have passed since a Fond du Lac police officer was gunned down in the line of duty. Officer Craig Birkholz was shot and killed while responding to a high risk domestic incident March 20th 2011. Police chief Bill Lamb says Birkholz arrived at the scene near Division Street and Lincoln Avenue shortly after 6:30 that Sunday morning and was shot seconds after exiting his squad car. Officer Ryan Williams was shot twice, but survived. Lamb says in the years since the shooting the Fond du lac police Department has placed active shooter training at the top of its priority list. A silent vigil marking the four year anniversary was held Friday at the law enforcement memorial at Hamilton Park.