BOGOTA, Colombia (AP) — Colombian officials said Friday they are starting efforts to take over about 25,000 acres (more than 10,000 hectares) of lands believed stolen by some of the country's most notorious paramilitary groups.

The head of the agency in charge of restoring stolen lands, Ricardo Sabogal, told The Associated Press that the 300 properties have been traced to the Castano Gil brothers who founded paramilitary squads in the 1980s.

Sabogal said that as the unit documented the history of the gang's victims, one name began popping up over and over in documents: Sor Teresa Gomez," the brothers' sister-in-law.

Sabogal said his National Unit for Restitution of Lands will launch judicial action to return the lands to the original owners, usually poor farmers.

The paramilitaries were founded to protect rich landowners from leftist guerrillas, but quickly branched out into crime, stealing lands and trafficking drugs.

Gomez was arrested last year. Prosecutors say she administered several of the paramilitary landholdings.

Since passage of a Victims Law in 2011, the agency has helped about 10,000 Colombians who were forced to abandon their lands due to pressure from paramilitaries, guerrillas or drug traffickers.

The government estimates that the various armed groups used force or fraud to gain control over at least 7,700 square miles (2 million hectares) of land.