Authorities say the two murderers who escaped from a maximum-security prison in northern New York conducted a practice run the night before they made their daring breakout.

Clinton County District Attorney Andrew Wylie says David Sweat and Richard Matt made a "dry run" of their escape plan on June 5 by going through an underground utility tunnel connecting Clinton Correctional Facility to the streets of Dannemora.

The men poked their heads out of a manhole, but decided it was too close to nearby homes. Instead, they exited the tunnel early the next morning through a slightly more isolated manhole located just a block from the prison walls.

Matt was shot to death last Friday in Malone by a border patrol officer. Sweat was wounded Sunday by a state trooper near the Canadian border.