A dozen leaders and members of a construction union were arrested Tuesday and charged with a decade of attacks against nonunion workers and their families, and prosecutors said some of the crimes were aided by the local's access to state motor vehicle records.

The president of Operating Engineers Local 17, Mark Kirsch, was among those charged with extortion and racketeering after a five-year investigation. The union, headquartered in Buffalo, operates in six western New York counties.

At job sites where non-Local 17 members were hired, union members caused more than $1 million in damage to more than 40 pieces of heavy machinery by pouring sand and grinding compound into the oil systems, breaking windows, destroying tires and cutting fuel lines, investigators said.

U.S. Attorney Terrance Flynn said investigators were particularly unnerved by the union's ability to run potential victims' license plates through the state Department of Motor Vehicles database to obtain personal information, including their wives' names and addresses.

The union had an account with DMV that was meant to allow it to ensure its own vehicles were properly registered and inspected, but the account was abused on several occasions, Flynn said. The practice abruptly stopped after investigators required the DMV to conduct an audit in 2006, he said.

A DMV spokesman had not heard about the allegations Tuesday and said he would look into them.

The U.S. Department of Labor, state police and FBI have been investigating the local since 2003; investigators say they traced criminal activity from 1997 to the present day. They allege threats and violence happened everywhere from the smallest house demolition to projects at high-profile sites, such as Ralph Wilson Stadium and Roswell Park Cancer Institute.

"It has caused losses in the millions economically ... and ultimately it has deprived western New York of vibrant economic growth," said Buffalo FBI Special Agent-in-Charge Laurie Bennett.

On one occasion, defendant James Minter III, a union organizer, told a worker entering a work site in July 2005, "Tell Tara you're going to be a little late tonight,'" referring to the worker's wife, the indictment said. In 2006, a Local 17 picketer allegedly yelled to a Uniland Development Co. representative that he was going to sexually assault his wife, naming the street the man lived on.

The president of one business reluctant to sign a collective bargaining agreement with Local 17 was stabbed in the neck and had his tires slashed in December 2002, according to the indictment. A little more than a month later, defendant Carl Larson, a union organizer, tried to persuade the businessman to sign the agreement. The conversation is recounted in court documents:

"What are the positives? You guys slash my tires, stab me in the neck, try to beat me up in a bar. What are the positives to signing? There are only negatives," the alleged victim said.

"The positives are that the negatives you are complaining about would go away," Larson responded.

A woman who answered two calls at the union's headquarters in the Buffalo suburb of Lakeview Tuesday declined to comment and said no one else was available. She did not know whether a lawyer had been retained to represent union members.

The indicted union members were taken into custody during a 5:30 a.m sweep of their homes. They include Gerald Franz Jr., who is listed on the union Web site as treasurer; Jeffery Peterson, listed as financial secretary, and Thomas Freedenberg, recording secretary. All are scheduled to appear in federal court Thursday. The most serious counts against them carry a maximum 20-year prison sentence.

Kirsch, Minter, Larson, Franz and Peterson all declined to comment when reached at their homes Tuesday and did not say whether they had lawyers. A number for Freedenberg could not be located.