Fallen officer Charles Knox was honored with a plaque near where he was killed in 1992. The plaque appears to have been removed, police say.

PHILADELPHIA (WPVI) -- A plaque dedicated to a fallen Philadelphia police officer has gone missing, and now investigators are trying to figure out what happened to it. The plaque was placed in memory of Ofc. Charles Knox, who was killed in the line of duty during the summer of 1992.

A Philadelphia police officer shot and killed a 47-year-old man in the Cobbs Creek section of the city Sunday evening, police said.Police identified the man as 47-year-old Jonathan Corbin in an update Tuesday afternoon.

Investigators are searching for a missing plaque dedicated to a fallen Philadelphia officer who was shot to death during an armed robbery over 30 years ago.

The memorial plaque of a Philadelphia police officer who died in the line of duty is missing and an investigation is underway, according to authorities. An investigation is ongoing into the disappearance of the plaque memorializing Officer Charles Knox from its sidewalk location in the 2000 block

The Philadelphia Police Department is asking for help in finding a missing memorial plaque that honors fallen Officer Charles Knox, who was killed in the line of duty in 1992.