ELIZABETHTOWN, N.Y. Law enforcement teams battled driving rain in upstate New York on Sunday in their manhunt for an inmate who escaped from a maximum security prison more than three weeks ago, after police shot and killed his accomplice on Friday.
 
Convicted murderer David Sweat, 35, was still at large after pulling off an elaborate scheme to break out of the Clinton Correctional Facility in Dannemora, New York, about 20 miles from the Canadian border. 
 
The manhunt has focused on the remote, heavily wooded area near the border in northern New York since Sweat's accomplice Richard Matt was shot dead by U.S. Border Patrol agents near Malone, about 27 miles (43 km) northwest of Dannemora.
 
Law enforcement agents working in heavy, steady rain were using infrared devices and listening posts to help flush out Sweat, authorities said.
 
Franklin County Sheriff Kevin Mulverhill said on Saturday that Sweat, who was serving a life sentence without parole in 2003 for killing a New York sheriff's deputy, would have to be fatigued, having had no regular meals or sleep for weeks. 
 
Matt and Sweat cut through their cell walls, climbed along a catwalk, shimmied through a steam pipe and emerged out a manhole outside prison walls, authorities said. They were discovered missing early on June 6.
 
Police traced Matt, who turned 49 on Thursday, to the Malone area when two burglaries were reported there last week at backwoods cabins.
 
On Friday, after Matt apparently fired a shot at a passing camping trailer, officers spotted and confronted him outside a cabin. They warned Matt to drop a shotgun he was holding and shot and killed him when he failed to comply, police said. 
 
Matt was convicted in the 1997 torture, murder and dismemberment of his boss in Tonawanda, New York.
 
Two prison workers have been charged with aiding in the escape. Gene Palmer, a 57-year-old corrections officer, is accused of bringing hacksaw blades and a screwdriver bit to the inmates, hidden in frozen hamburger meat supplied by Joyce Mitchell, 51, a training supervisor in the prison tailor shop.