A convicted murderer who broke out of prison and went on the run for more than three weeks before being shot and captured has told police that he and a fellow escapee conducted a practice run the night before their daring breakout, a district attorney said.

Clinton County District Attorney Andrew Wylie said David Sweat, 35, told police from his Albany Medical Center hospital bed that he masterminded the June 6 breakout from Clinton Correctional Facility and began working on it in January.

The escape by Sweat and 49-year-old Richard Matt launched a massive 23-day manhunt amid the rugged northern New York terrain involving more than 1,100 law enforcement officers.

Matt was shot and killed by a border patrol officer June 26 in Malone. Sweat was wounded Sunday by a state trooper near the Canadian border. He was listed in fair condition Wednesday.

Wylie said Sweat claimed he used only a hacksaw blade — not power tools, as officials had reported — to cut holes in the steel walls of his and Richard Matt's cells as well as a 24-inch steam pipe they crawled through.

Wylie said Sweat claimed to have done all the work himself, saying the older Matt wasn't in shape to do it. Sweat said he prowled the tunnels within the maximum-security prison from 11:30 p.m. to 5 a.m. — after lights-out and before the morning headcount — in the days preceding his June 6 escape with Matt, according to Wylie, who was briefed by state police on the surviving inmate's statements.

Authorities said the two reached the tunnels via an interior catwalk — narrow utility corridors between cellblocks providing access to the bowels of the prison — they were given access to by a corrections officer who has since been charged in connection with the escape.

"He said he had been out in the catwalk area for a couple of weeks" before the breakout, Wylie said.

Wylie said the two convicts conducted a practice run the night before they escaped. He said the "dry run" on June 5 took them through a tunnel connecting the prison to the streets of Dannemora, 20 miles from the Canadian border.

The men poked their heads out of a manhole but decided it was too close to nearby homes, Wylie said. The next day, they exited the tunnel through a manhole that was slightly more isolated despite being located in the middle of an intersection just a block from the prison walls, he said. The second manhole can be seen from a window in the prison tailor shop where the two convicts worked.

Officials said a tailor shop employee, Joyce Mitchell, got close to Sweat and Matt and supplied them with hacksaw blades and other tools. She agreed to be their getaway driver but backed out at the last moment, authorities said. She has pleaded not guilty.

A prison guard, Gene Palmer, told investigators he gave the convicts tools, art supplies and access to a catwalk electrical box in exchange for paintings by Matt. But he said he never knew of their escape plans.

The prison's superintendent, his deputy and 10 other Clinton employees have been placed on leave.