Authorities in Indiana announced on Friday that the mission to find a 16-year-old boy who went missing last month has shifted from a search to a recovery effort.

Robert “RJ” Williams Jr., for whom a Silver Alert was activated, was last observed on December 17 in Indianapolis. According to a statement given to the Indianapolis Star, the Indianapolis Metropolitan Police indicated that recent developments suggest Williams may have accidentally entered the White River.

A day following Williams’ disappearance, investigators located his gym bag and backpack on a dock adjacent to the White River. Despite extensive searches using ground teams, drones, sonar, and watercraft, Williams has not been found, reports the Indianapolis Star.

Williams was initially reported missing when he did not return home from Purdue Polytechnic High School. It’s believed that he visited a McDonald’s before he disappeared.

Described as autistic with a mild intellectual disability, Williams is said to have the cognitive capacity of a 10- or 11-year-old. He also has a history of psychosis and disruptive mood dysregulation disorder.

Williams was described as standing 5 feet, 9 inches tall, weighing 185 pounds, and having black hair with brown eyes. He was last seen wearing a gray coat, blue sweat pants, and black tennis shoes.

Police did not say what new evidence led to the shift in their investigation. WTHR reported that search teams are expected to return to the White River on Friday.

“If what is being said is true, Robert passed away on Dec. 17,” Williams’ mother wrote in an online post. “My heart is shattered as I am more than broken. Today is the day, RJ, and today is going to be a very hard day for many of us. If what the detectives are saying is true, please allow them to find you.”

[Feature Photo:  Indianapolis Metropolitan Police Department]