U.S. attorney adds Mahony to his file

LOS ANGELES AND WASHINGTON — In the 16 months since he was sworn in as U.S. attorney in Los Angeles, Thomas P. O'Brien has charged a former U.S. Marine with manslaughter for combat killings in Iraq, tried a Missouri woman whose alleged crime, many would argue, was committed halfway across the country and sought to strip a notorious outlaw motorcycle gang of its very identity.

Now he has immersed himself in a grand jury investigation into Cardinal Roger M. Mahony's handling of sexually predatory priests in the Archdiocese of Los Angeles.

In each of these cases, O'Brien, a former Navy Top Gun instructor and gang prosecutor in the district attorney's office, has either taken on battles that others may have shied away from or employed novel -- some would say shaky -- legal strategies to make his case.

Mahony said in a radio interview Thursday that he was "mystified and puzzled" by news of the probe.

The results of O'Brien's previous prosecutorial pursuits have been mixed. In the case of the ex-Marine, O'Brien's office used a law intended for prosecuting soldiers' spouses or civilian Department of Defense employees living in foreign countries to try Jose Luis Nazario for the killings of four unarmed Iraqi prisoners in Fallouja. Nazario had left the Marines and was no longer a reservist, meaning he was not subject to a court-martial. Rather than simply let him go, O'Brien tried Nazario in civilian court, the first such case in modern history. The case angered some former Marines, who said civilians jurors were not capable of fairly judging decisions made in combat. Nazario was acquitted.

In another case, Lori Drew, the Missouri mother accused of perpetrating an Internet hoax that prompted the suicide of a teenage girl, was charged under a statute more commonly used to go after computer hackers. She was acquitted of the felony charges against her but convicted of three misdemeanors. She is awaiting sentencing, but the judge is considering whether to dismiss the case altogether on grounds that, despite the jury's verdict, prosecutors failed to make their case.

In the Mongols motorcycle gang case, O'Brien's office claimed the rights to the gang's trademarked emblem, empowering officers to seize -- on the spot -- jackets, motorcycles and other items members use to identify themselves.

Rebecca Lonergan, a former federal prosecutor who worked under O'Brien in the U.S. attorney's office and now teaches law at USC, said "there is no doubt that his prosecutions have been very aggressive."