The U.S. Justice Department will investigate whether Miami police violated the constitutional rights of seven black men who were shot to death by officers over an eight-month span, raising tensions in the inner city and sparking demands for an independent review.

The civil investigation — known as a “pattern and practice’’ probe — will examine Miami police policies and training involving deadly force. The goal: to determine if systemic flaws made shootings of black men more likely, rather than unfortunate, last-choice actions, as the officers’ supporters maintain.

A source close to the investigation confirmed Wednesday night that Thomas E. Perez, head of Justice’s civil rights division, and Miami U.S. Attorney Wifredo Ferrer will announce the investigation during a press conference in downtown Miami Thursday morning.

Family members of the deceased, church leaders and activists have been invited to meet with Ferrer Wednesday afternoon, but they were not told why. They reacted with relief when told the news.

“Oh, that’s great, great, really good,” said Sheila McNeil, whose unarmed son Travis McNeil, 28, was shot to death in his car in Little Haiti Feb. 10 by Officer Reinaldo Goyo. The officer said McNeil was driving erratically. No weapon was ever found.

“I’m just glad to know it’s not forgotten,’’ McNeil told The Miami Herald. “Right now I don’t know more than I did the night he died, so I’m just waiting to hear what they have to say.”

But Nathaniel Wilcox, executive director of People United to Lead the Struggle for Equality, or PULSE, who has stood with many of the dead men’s families during a series of emotional public meetings, criticized federal authorities for not opening a criminal investigation into the shooting deaths. They spanned July 2010 to February 2011.

“We think they really took too long and we feel abandoned,’’ Wilcox said. “We expected the Obama administration to do a lot more and a lot quicker than they did.”

The Justice Department will not conduct criminal investigations into the seven shootings, which are under review by the Miami-Dade State Attorney’s Office. But Justice will look into the Miami Police Department’s training methods, leadership and practices. Any adverse findings could lead to court-enforced reforms, but more frequently, Justice works with a police department to iron out any problems.

The U.S. Attorney’s Office in Miami declined comment Wednesday.

Acting Miami Police Chief Manuel Orosa did not respond to interview requests. But spokesman Delrish Moss said the department is being revamped under the new chief, who assumed the post in September and is conducting a “top to bottom review of everything, from training to hiring.”

Miami Mayor Tomás Regalado did not return calls.

The impending investigation marks the second time in a decade that federal authorities have conducted an investigation into alleged systemic violations of constitutional rights by Miami police officers.

In 2002, Justice conducted a much broader civil probe, concluding in 2003 that the department had serious flaws in the way it conducted searches and seizures, used firearms, defined use of force and worked with police dogs. The inquiry began at the city’s request after several controversial police shootings.