The man accused of driving drunk and causing a collision that killed a nun was allowed to work in the United States, even though he was about to be deported for a previous drunken driving conviction, the police chief of Prince William County, Va., said Friday.

Chief Charlie Deane said U.S. immigration officials gave Carlos Martinelly-Montano, 23, an employment authorization card Jan. 14, 2009, just months after he entered deportation proceedings. Deane’s disclosures came in a recent letter to John Morton, head of U.S. Immigration and Customs Enforcement. Deane made the letter public Friday.

Martinelly-Montano’s case became a rallying point for advocates of stiffer immigration enforcement after his car swerved last month into the path of a vehicle carrying three nuns.

Prince William Commonwealth’s Attorney Paul Ebert said he intends to ask a grand jury to return a second-degree murder indictment.

Sister Denise Mosier, 66, died in the crash.

Martinelly-Montano entered the United States illegally at age 8 with his parents and sister. He had been awaiting a deportation hearing after two drunken-driving convictions, in 2007 and 2008.

While Martinelly-Montano was jailed in the second drunken-driving case, Deane said, ICE was notified and an immigration detainer was issued. Deportation proceedings began, but Martinelly-Montano was given the employment card, Deane said. He used the card to get a valid Virginia ID card, Deane said.

Deane also said Martinelly-Montano used a previously issued employment card to obtain a driver’s license. An employment authorization card is not a green card, which indicates permanent legal residence.