Less than three hours after he allegedly shot and fatally wounded a Capitol Heights woman on Wednesday, Keith Arnez Boone answered the phone in his Beltsville apartment. A computer from a private home detention firm was calling to make sure Boone was home for the night and not out on the streets.

The computer recognized Boone's voice, so he passed the test. Six hours later, the computer randomly selected Boone for another phone check on his whereabouts. Once again, he passed. As far as the home detention firm was concerned, nothing was amiss and Boone had met the terms of his one-year home detention sentence, the result of a January conviction for cocaine possession.

Late Thursday, Prince George's County police arrested Boone at a Baltimore motel and charged him with first-degree murder in the death of Dona Elizabeth Ferguson, 40, a mother of five children who was struck in the chest by a stray bullet as she was hanging curtains in her living room. Police said Boone, 21, had aimed the shot at a 19-year-old man whom he and three friends were chasing in retribution for a drug deal gone sour.

At the time of the shooting, Boone was being supervised by Home Tracking Inc., an Upper Marlboro home detention firm that monitors criminal suspects and convicts who are confined to their homes during certain hours.

Jerry Romer, co-owner of Home Tracking, confirmed yesterday that Boone was one of his clients. Although Romer said it was regrettable that one of his clients had been charged with murder, he questioned whether there was anything more his firm could have reasonably done to track Boone or to keep him out of trouble.

"He was there at home when he was supposed to be, doing what the system asked him to do," Romer said. "Nothing's perfect. Nothing's going to stop these guys if they really want to be devious and find a way around the system.

"This comes up all the time: How do you know where these guys are? You don't. How can you control them? You can't. Are we all sorry? Yeah. Should we have put Keith Boone in jail? Yeah, in hindsight."

Romer said that, according to the conditions of home detention, Boone was allowed to go to work each day and was supposed to be home each night from 7 p.m. to 7 a.m.

Police said Ferguson was shot about 6:20 p.m. Wednesday. Romer said that his office computer randomly called Boone twice that night--at 9 p.m. and about 3:30 a.m.--and found he was home each time. Romer said that all checks on Boone were made by telephone and that he was not outfitted with an electronic monitor or visited at his home.

Romer said he didn't know that Boone might have done anything wrong until Thursday, when he was watching the evening news and saw that police were looking for Boone and had a warrant for his arrest in Ferguson's death.

The practice of allowing criminal defendants to serve their terms or await trial while under home detention has faced harsh criticism before in Maryland. In 1996, an armed robbery suspect allegedly raped three women and robbed two others while under the watch of a privately run electronic-monitoring program.

That case spurred Maryland lawmakers last year to pass legislation that for the first time would regulate and license private home-detention firms. Broad terms of the legislation are supposed to take effect July 1, but the Maryland Commission on Correctional Standards is still weighing specific guidelines for the industry. A public hearing on the guidelines is scheduled for June 29.

For instance, there is still no standard governing how home detention firms are supposed to keep track of their clients.

Del. James W. Hubbard (D-Prince George's) criticized the state legislation for not spelling out which types of defendants should be eligible for home detention and for not requiring all private companies to use electronic devices as a tracking tool.

"If we're going to put people out there who have these kinds of backgrounds, we need to have some strong standards," Hubbard said. "We better make sure we have electronic monitoring devices so we know where all these people are every minute of the day. If not, then it's just a sham."

Local governments have been running home detention programs in the Washington area since the mid-1980s. Private companies began to offer similar services soon after when the government programs began to fill up.

Although judges can sentence defendants to serve their time in home detention, they rarely attach specific conditions, leaving it up to the companies to decide. The private companies do not receive any money from the courts or other government agencies; rather, they collect money directly from the defendants, usually $8 to $12 a day.

Court records do not specify the terms of Boone's home detention, except to say that he was required to enroll with a private home-detention company within 30 days of his sentencing Jan. 11.

Romer refused to say whether Boone enrolled within the court-ordered time period or to give further details of his case. "There's no easy answer for that one," Romer said. "Eventually, he did enroll. Let's leave it at that."

Two days after he was sentenced Jan. 11 on the cocaine possession charge, Boone was arrested again after Prince George's police found 128 grams of crack cocaine in his car. Although he was on probation at the time, Prince George's District Court Judge Gerard F. Devlin set his bond at $25,000, and Boone was released. His trial on those charges is scheduled for next month.

Devlin said yesterday that he didn't recall the specifics of Boone's bond case. But he said he usually agrees to set bond for suspects if they are not accused of violent crimes and if they have hired private lawyers.

"As bad as drug dealing is, it doesn't compare to murder," he said. "Really, when it comes to bail review, the only elements are: 'Will he show up?' And the general feeling on that is if someone has gone to the trouble of hiring a lawyer, they usually don't commit crimes while on bond."

At a routine bail review hearing yesterday, Devlin ordered Boone and two co-defendants in the Ferguson murder case--Ronald Degaulle Rice Jr., 33, of Capitol Heights, and Leroy Dump Smith, 46, of Amherst, Va.--held without bond. Devlin set bond at $20,000 for a fourth defendant, Ronald Degaulle Rice Sr., 59, also of Capitol Heights.

Staff writer Ruben Castaneda contributed to this report.

CAPTION: Keith Arnez Boone is accused of killing a woman who was hanging curtains.