BARRETT TWP. — The donated, high-tech helium balloon used to assist in the search for an accused cop killer is back in Ohio.

The rugged terrain and heavy tree canopy in the wooded area in Monroe County where authorities are looking for Eric Matthew Frein hampered the large surveillance balloon’s usefulness in finding the 31-year-old Canadensis man, Trooper Tom Kelly, a state police spokesman said in an email. Because of that, state police returned the balloon to the Ohio Department of Transportation on Tuesday.

The search for Mr. Frein, of 308 Seneca Lane, entered its 47th day Tuesday. Mr. Frein, considered armed and dangerous, is the sole suspect in the Sept. 12 sniper attack at the Blooming Grove state police barracks in Pike County that killed Cpl. Bryon K. Dickson II of Dunmore and wounded Trooper Alex T. Douglass of Olyphant. Police believe he is hiding out in state forest near his home.

— JOSEPH KOHUT