He enlisted in the Pennsylvania State Police from Harrisburg on May 22, 1969, and was assigned to Troop F, Montoursville. He was 24 years old and 5'11½" tall.

At 4:50 p.m. on December 12, 1970, Trooper Rosenberger was engaged in undercover duty on a narcotics investigation. He was shot nine times and died instantly. Trooper Rosenberger's body was found in a small stream in Old Lycoming Township, Lycoming County. Barney L. Russell of Williamsport was arrested and charged with Trooper Rosenberger's murder. Russell was 19.

Trooper Rosenberger was buried with full military honors at Paxtang Memorial Cemetery. More than 100 Troopers made up the official funeral escort. Representatives from 24 other police agencies and 12 states also attended to pay their respects. He was survived by his wife, Mrs. Molly Rosenberger, of Hummelstown. Two trust funds were immediately established to aid Mrs. Rosenberger and her 4 month-old daughter, Nicole.

On January 13, 1971, Mrs. Rosenberger was awarded the Pennsylvania State Police Cross, a medal presented to the next of kin of a Trooper killed in the line of duty. At 26, Trooper Rosenberger had completed one year and seven months of Pennsylvania State Police service.