Pennsylvania state police say they have a new silent ally in their search for suspected cop-killer Eric Frein -- an unmanned balloon equipped with high-resolution cameras. The Ohio State Department of Transportation has loaned the “eye in the sky” to act as a quieter, low-cost alternative to helicopters and other methods of aerial surveillance.

Hundreds of state troopers have taken part in the manhunt for Frein, 31, who they suspect is hiding somewhere in the woods of northeastern Pennsylvania. The “survivalist” allegedly ambushed state police barracks on Sept. 12, killing Trooper Bryon Dickson and wounding Trooper Alex Douglass. The 45-day manhunt costs roughly $500,000 every week it persists.

The balloon had been scanning Ohio prisons for potential fugitives, and will be tethered nearly 500 feet above the Pocono Mountains, where Frein is thought to be hiding following a number of unconfirmed sightings. It is 15 feet in diameter and made of Mylar, and costs only $1,000 to deploy, according to Fox News, compared to noisy police helicopters, which cost nearly $2,500 an hour.

The balloon’s cameras can spot people over 3 miles away. Police officials say they believe Frein is pinned down in an area stretching more than 5 miles.