A manhunt is growing as the search for the suspect in the shooting death of a Pennsylvania State trooper goes into its fourth day Monday.

Investigators from New Jersey and New York, as well as federal officials, have joined the search party that is looking for the person who killed Cpl. Byron Dickson and critically wounded Trooper Alex Douglass, USA Today reported.

The officers were shot just before 11 p.m. Friday about 35 miles east of Scranton, Pennsylvania. The two men were shot in what investigators say was an ambush targeting the officers. So far the search has not been fruitful.

"There has been an exhaustive search conducted by hundreds of members of law enforcement," said Lt. Col. George Bivens. "We have canvassed the wooded areas, neighborhoods. We are convinced this individual is no longer in that immediate area."

The search is now focused on eastern Pennsylvania, with officials from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives helping the state effort. Anyone with information is asked to call police at 866-326-7256. Pennsylvania Crime Stoppers is offering a $50,000 reward for tips that lead to an arrest.

Over the weekend, police were looking into a man named Jeffrey Dudek, calling him a person of interest.

"We've received many tips and they're being assigned (to investigators) as we speak,'' state police spokeswoman Connie Devens said. "He's still a person of interest, but no charges have been filed," she said about Dudek.

Douglass was still in critical condition following surgery on Sunday at Scranton's Geisinger Medical Center. His condition had stabilized following the procedure.

Dickson's funeral will be held on Thursday morning at a Scranton Roman Catholic church, according to a Fox News report. He was a seven-year veteran of the state police and is survived by his wife and two young sons.