Vice President Biden and Attorney General Eric H. Holder Jr. on Wednesday will unveil a new domestic violence initiative and award $2.3 million in grant money as part of a new effort to reduce gun violence, according to a White House official.

At an event in Rockville, Biden and Holder plan to introduce the Domestic Violence Homicide Prevention Demonstration Initiative — a Justice Department program modeled after state initiatives in Maryland and Massachusetts and intended to help municipalities monitor high-risk offenders and identify potential victims.

The aim is to identify women who may be in potentially fatal abusive relationships and connect them with law enforcement officers, prosecutors, court personnel and other service providers in a position to protect them. Twelve jurisdictions will get one-year grants of as much as $200,000.

The initiative was detailed by a White House official who spoke on the condition of anonymity because a formal announcement had not been made. Biden and Holder will announce the program at the Montgomery County Executive Office Building.

Forty percent of mass shootings in the past three years started with the gunman targeting his girlfriend, wife or ex-wife, according to the White House official.

Federal law prohibits domestic violence offenders from possessing firearms, but not every state requires background checks for gun purchases, meaning that many offenders are still able to buy guns.

The federal initiative is modeled after the Maryland Network Against Domestic Violence, which enlists police, health clinics and faith groups to identify women at the most risk of abuse and connect them to domestic violence services. The homicide rate linked to domestic violence in Maryland has fallen 34 percent in the past five years, the official said.

The federal grants will go to Contra Costa County, Calif.; Miami-Dade County, Fla.; Palm Beach County, Fla.; Rockdale County, Ga.; Winnebago County, Ill.; Boston; Brooklyn; West­chester County, N.Y.; Pitt County, N.C.; Cuyahoga County, Ohio; North Charleston, S.C.; and Rutland, Vt.

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