The unmanned balloon came from Ohio and was supposed to be quieter than a helicopter and provide similar technology to aviation equipment being used in the search, but at a lower cost, police said. But it was returned just a day later, police said today.
"Due to the tree canopy and rugged terrain of our search area the balloon was not as helpful as everyone hoped it would be," said Trooper Tom Kelly, a spokesman for the Pennsylvania State Police.
The balloon was the latest tactic police employed in the ongoing search for Frein, accused of killing one state trooper and injuring another when he allegedly ambushed the Blooming Grove police barracks on Sept. 12.
Police believe he's been hiding in the woods for nearly seven weeks.