Days before she was to be sentenced for one of the country's most egregious environmental crimes, North Andover resident Albania Deleon begged for the court's mercy.

"I pray that God will forgive my soul," she wrote in a three-page handwritten letter to US District Court Judge Nathaniel M. Gorton, "and allow me to atone the rest of my life repaying and repairing the harm I have done. This is my solemn promise."

Then the 39-year-old mother sawed off her ankle monitor and disappeared into a cool March day, becoming one of the US Environmental Protection Agency's most wanted fugitives.

Deleon left behind not only her 3-year-old son, but hundreds, maybe thousands, of people who face a heightened risk of lung cancer because of her crimes.

Deleon operated New England's largest asbestos removal training school out of an attractive downtown Methuen storefront from 2001 to 2007. But training was a misnomer: Instead, Deleon and her assistants would often simply sell, for $400, certificates saying the holder was qualified to remove insulation, flooring, and other construction material containing deadly asbestos fibers. Federal officials estimate at least 2,500 people received fraudulent certificates from Deleon.

Those people - most illegal immigrants, according to federal officials - then went in to hundreds of schools, hospitals, churches, libraries, and homes throughout New England to remove asbestos. Most of them lacked training in even the most basic safety precautions.

Officials believe the heath risks to people in those buildings - from Beverly High School students to Roslindale Public Library patrons - are minimal; most were not directly exposed to the asbestos-laced dust kicked up in the removal process. But there is deep concern that the workers, most of them young men from Central America, breathed the fibers, which can lodge in the lungs and lead to death decades later. Many of those workers, it turned out, had never even been told how to properly wear a respirator.

Equally troubling is that they may have exposed their families to the cancer risk. Asbestos workers, if not properly trained, can inadvertently carry the fibers home on their clothes or hair.

"The scope of this is enormous," said Michael Hubbard, special agent in charge of the EPA's Criminal Investigation Division in New England, whose office arrested Deleon in 2007. "And the biggest victims in this entire house of greed are the illegal aliens who did not receive training and were placed in very hazardous working conditions - many did not know what they were dealing with."