Ruslan Burshteyn stood in a Burlington County courtroom Friday and thanked prosecutors for aggressively pursuing a case against Lenroy Laurance, an undocumented Jamaican immigrant who killed his mother in 2009 because he wanted her car.

His mother, Lyudmila, and her family were Russian Jews who came to the United States years ago because they believed in "the fairness of the system" here, Burshteyn said. The family was granted asylum because it had suffered religious persecution.

Now, Burshteyn said, he has seen "both the good and bad" sides of the U.S. justice system.

While waiting two years for the trial to begin, Burshteyn learned that authorities knew Laurance was an illegal immigrant when he previously served jail time in Brooklyn, N.Y., for selling drugs.

"How is it possible someone would let him go free?" Burshteyn asked.

A convicted felon found to be in the country illegally is normally subject to deportation, according to federal authorities. Had that happened in Laurance's case, Burshteyn said, his mother might still be alive.

Laurance was convicted in October of carjacking Lyudmila Burshteyn, 57, in Frankford, then shooting her in a remote field in Mansfield Township.

Khaalid Walls, spokesman for U.S. Immigration and Customs Enforcement (ICE), said Laurance's situation was not unique. There are "difficulties involved in deporting illegal aliens," he said in an e-mail.

Before ICE can send a felon home, it must get "travel documents" from the country of origin, he said.

If birth certificates can't be located, if a country refuses to issue the required documents, or if there is another obstacle that would prevent deportation within 180 days, ICE must release that person, he said.

The Supreme Court, Walls said, has ruled that felons who are undocumented immigrants may not be confined indefinitely unless they pose a national security threat or meet other limited criteria.

During the time the felon is free, ICE continues to work on getting the paperwork in order. The felon is supposed to check in periodically, Walls said.

At one point after an earlier incarceration, Laurance - who also was convicted of a robbery before the murder - went AWOL. Jamaica is one of 27 countries that delay the removal process, making it difficult for ICE to do its work, according to immigration officials.

On Friday, Superior Court Judge Jeanne T. Covert sentenced Laurance to life imprisonment plus 40 years.

"The system does work," Ruslan Burshteyn said afterward. "The effort by the prosecutors and the investigators is enormous."

First Assistant County Prosecutor Ray Milavsky said Lyudmila Burshteyn was a sterling example of an immigrant who deserved respect. After coming to the United States, she went to night school to learn English, raised a family, and became a successful businesswoman, he said.

Though Laurance also was "born on foreign soil," Milavsky said, he was nothing like Burshteyn: "This man never worked a day of honest work during the time he was in the U.S. . . . He boasted he was a career drug dealer."

Contact staff writer Jan Hefler at 856-779-3224 or jhefler@phillynews.com or @JanHefler on Twitter. Read her blog at www.philly.com/BurlcoBuzz.