In 2002, three troubled youths removed older versions of the monitoring devices and were charged with killing people in separate incidents.
The state has invested $1 million in the GPS technology, and Brown said about 200 juveniles at any given time are being monitored around the clock.
"We have been able to save lives," Brown said.
Davis had several arrests, dating back to age 10, though he had been found guilty - or "sustained," as it is referred to in juvenile court - only a handful of times. Sources say he had been released from a group home in Oxon Hill in December after showing improvement, and he was working with a mentor.
He was first charged June 2002 with assault with a deadly weapon, which was eventually dismissed. Charges of attempted theft, heroin and cocaine distribution, and auto theft were each dismissed. An auto theft case in July 2006 was sustained and he was placed on juvenile probation.
Another auto theft charge, from October 2006, was dismissed, and in October 2007 he was charged with armed carjacking after a man reported that three juveniles ordered him out of his car at a traffic light. He admitted to a charge of "fleeing and eluding."
In May 2007, a 13-year-old who said she was his girlfriend told police that he accosted her on the street, telling her that her pants were too tight and instructing her to change clothes. When she refused, she said, she was struck several times in the stomach and face. An officer wrote in a police report that after Davis was arrested, he said he "would get a knife and kill his pregnant girlfriend" when he was released.
In February 2008, he was committed to the custody of Juvenile Services, but he would be charged several times in the months that followed. In June 2008, he was picked up on a trespassing charge; in December, he was arrested and eventually admitted a drug possession charge. In January 2009, he was charged with second-degree assault, and on May 29, he was charged in the robbery.
