SAN DIEGO -- A nursing home resident who tried to kill or seriously injure roommates and tenants at two facilities by setting a series of fires, including one in a suite-mate's bed, was sentenced today to 19 years in prison.

Mary Louise Wilson, 54, pleaded guilty Jan. 5 to two counts of attempted murder, three counts of arson, two counts of attempted arson and one count each of assault with a deadly weapon for threatening a resident with a knife and making a criminal threat with a deadly weapon.

Last August, the office of state Attorney General Jerry Brown, along with the National City Fire Department and El Cajon Police Department, began an investigation into a series of fires set in nursing homes in the San Diego area.

"These fires were no accident," Brown said. "This woman meant to kill or seriously injure dozens of disabled people. Residents of nursing homes are particularly vulnerable, so today's sentence is an important victory in our fight against elder abuse in California communities."

The first fire occurred in January 2009 at El Dorado Care in El Cajon. Wilson, a resident there, had been placed in a room with two other women -- neither of whom could get in or out of bed without nursing assistance. One of them was attached to an oxygen tank.

In the middle of the night, Wilson set fire to the bed of one of her roommates while the woman was sleeping. A nurse heard the smoke alarm and used a fire extinguisher to put out the blaze before anyone was hurt.

Four months later, Wilson was transferred to Golden Paradise Senior Living, an assisted living center in National City.

Soon after she arrived, Wilson set fires in the second-floor trash chute, the first-floor Dumpster and the second-floor library, according to authorities. She also threw burning materials down the trash chute.

Firefighters from National City and the building's sprinkler system doused the fires before anyone was hurt.

Investigators from the Attorney General's Office identified Wilson as a suspect by linking the fires at the two facilities.