When an illegal immigrant was accused last year of driving drunk and causing a crash in Prince William County that killed a nun, the case unleashed a wave of anger and became a touchstone for supporters of stricter immigration enforcement.

With the murder trial of Carlos Martinelly-Montano set to begin in the county’s Circuit Court on Monday, the political reverberations of the case are still playing out and will probably do so long after the verdict is read.

“The case has become a hallmark,” said Claire Gastanaga, a former Virginia chief deputy attorney general and a lobbyist for immigration advocacy groups. “It has become a place holder for a lot of different things that people are unhappy about with the immigration system.”

Melissa Sanchez, Martinelly-Montano’s attorney, said he is expected to plead guilty to five of the six charges he faces but intends to plead not guilty to the most serious charge, felony murder.

Police said Martinelly-Montano, 24, of Bristow slammed his car into another with three nuns inside about 8 a.m. on Aug. 1, 2010. The crash on Bristow Road in Bristow killed Sister Denise Mosier, 66, and seriously injured Sisters Connie Ruth Lupton and Charlotte Lange. All three belonged to the Benedictine Sisters of Virginia, who have a monastery in the town just west of Manassas.

At the time of the crash, Martinelly-Montano, who came to the United States from Bolivia as a child, had awaited a deportation hearing for almost two years after convictions in 2007 and 2008 for driving under the influence of alcohol. He was not being held because immigration authorities did not deem him a flight risk and there were few beds available at D.C. area detention centers.

The revelation prompted outrage and a flurry of changes. Prince William County Supervisor Corey A. Stewart (R-At Large), who led the charge for increased immigration enforcement in the county in 2007, released a statement saying President Obama and Congress had “blood on their hands.”

Virginia Attorney General Ken Cuccinelli II (R) issued an opinion saying police could inquire about a person’s immigration status during stops or arrests, Virginia changed the rules on issuing state IDs, and the Department of Homeland Security launched a probe of Martinelly-Montano’s case.

The DHS probe concluded that Martinelly-Montano’s situation probably would not be repeated today because the department is more aggressively deporting illegal immigrants with criminal records. Immigration authorities say they have added 500 beds at detention facilities in the D.C. area and have decreased the time it takes to get a hearing in cases in which someone is not being detained.

Stewart is skeptical. Prince William County filed a lawsuit in August to try to determine the fate of 4,000 illegal immigrants it turned over to DHS. That case is pending in federal court in Virginia.

“I would love to say there has been progress within DHS, but we can’t say that because we don’t have the data,” Stewart said.

Crystal Williams, the executive director of the American Immigration Lawyers Association, said the biggest change that has come about in the wake of the Martinelly-Montano case is an aggressive crackdown on illegal immigrants who have drunken driving records.

“There is a more categorical approach to anyone who has a drunk driving violation. You’re not seeing as much evaluation of individual cases,” Williams said. “It’s drunk driving — he’s done.”

Some thought Martinelly-Montano’s case might be Virginia’s “Arizona moment”: Last year, the killing of a prominent rancher there sparked the passage of one of the nation’s strictest immigration enforcement laws. So far, that has not happened.

This year, a bill that would have allowed police to check the immigration status of people who were arrested was passed by Virginia’s House of Delegates but failed in a state Senate committee. Stewart said the bill should be reintroduced during the next session, and he believes it could pass if Republicans wrest control of the state Senate from Democrats.

Others think a backlash is building against such legislation.

They see Arizona’s experience as a cautionary tale. Arizona has been hit by protests and boycotts and had a dramatic decrease in the meetings and events business after the law’s passage. Some law enforcement officials also say such laws hurt their relationship with immigrant communities.

In Prince William County, opponents of the county’s strict enforcement policy said it has caused immigrants to flee the area and has hurt property values.

“There is a lot more debate of the unintended consequences of these laws and how they affect the community,” said Ann Morse, who oversees immigration issues for the National Conference of State Legislatures.

As the immigration debate simmers, the Benedictine sisters have decried the politicization of the crash. Shortly after the accident, the nuns’ spokeswoman said Martinelly-Montano “deserves to be treated with respect.” When Martinelly-Montano’s parents made an unexpected visit to the monastery last year, the nuns told them they had forgiven him.

The two injured sisters have quietly gone about getting their lives back on track. Both have recovered physically and have begun to work again. Lupton tends the sisters’ home in Bristow, while Lange is providing spiritual counseling for hospital patients in Richmond and was recently honored by Commonwealth Catholic Charities for her volunteer work.

The sisters declined to be interviewed pending the outcome of the trial, but Dougal Hewitt, Lange’s supervisor in her hospital work, said he has noticed a change in her since that tragic morning.

“If anything, she is more committed to the sick, under-served and vulnerable,” Hewitt said. “Her understanding of the preciousness of life is even deeper.”