NEW YORK: The upstate New York prison break of two inmates who squeezed through underground pipes last weekend was among a handful of recent daring escapes by US convicts whom experts describe as ingenious and willing to risk it all to flee a life behind bars.

Escape schemes as cunning as slipping out of prison in a mail sack or using a can opener to cut through the ceiling of a jail house kitchen have been employed in the past decade.

Escapees have got “imagination, they’re creative, they’re intelligent and they’re willing to risk their lives,” said Charles Ewing, a law professor at University at Buffalo who specializes in forensic psychology and violent behavior.

Jeff Hall, a history professor at Queensborough Community College who has studied prisons blamed cutbacks in education programs aimed at rehabilitating prisoners, such as those offering high school and college degrees, for creating a void in which escapes serve as one of the only mental challenges.

“Opportunities for wild imaginings becoming reality are greater now that prisoners’ minds are effectively being wasted and their potential abilities and gifts are being squandered,” Hall said.

Authorities for a seventh day on Friday are searching for convicted killers Richard Matt, 48, and David Sweat, 34, who were discovered missing from Clinton Correctional Facility in Dannemora, New York, about 5:30 a.m. on June 6. They had busted through metal walls, crawled through pipes and popped out a manhole on the street. On their way out, they left a taunting note, “Have a nice day!“

Similarly audacious was a December 2007 escape by two prisoners from a New Jersey lockup who left behind a note, “Happy Holidays!” with a drawing of a character making an obscene hand gesture.