Eleven years ago when he was a part-time Arlington deputy sheriff, Henry Hudson says "I couldn't imagine knowing the commonwealth's attorney, let alone being one."

Since January that is precisely what Hudson has been -- the county's chief prosecutor.

A Northern Virginia native whose sober demeanor and conservative outlook belies his youth -- he is 33 -- Hudson once told a reporter that "I'm a prosecutor; I live to put people in jail."

Hudson appears to be successful. The conviction rate achieved by his office is estimated to be 90 percent.

In the six month since he took command after trouncing his former boss, controversial Democratic incumbent William S. Burroughs Jr., by more than 5,000 votes, the Republican-backed Hudson has won widespread praise for his competence, administrative skills and willingness to work hard.

But critics say they are concerned about Hudson's enthusiastic use of undercover informants, his hard-line philosophies -- particularly toward drugs -- and his close personal friendships with police officers.

Unlike his predecessor Burroughs, who spent much of the last two years of his term embroiled in a bitter public feud with the police department and Virginia Attorney General J. Marshall Coleman over a celebrated 1977 double murder case, Hudson has strong ties to the police.

"Henry is a policeman's prosecutor," said his friend U.S. Attorney Justin Williams. Hudson, who once carried a gun while serving as an assistant U.S. prosecutor, listens to a police radio in his office.

"Henry is really an in-house guy around the courthouse much more than Bill Burroughs was," said Circuit Court Clerk David A. Bell, who has known Hudson for 10 years.

"The judges really like Henry," added another Arlington official who has watched his ascension from a $20 per day deputy sheriff to the $41,000-a-year post of chief law enforcement officer. "Burroughs spent a lot of time lobbying in Richmond and he would sponsor things like gun control which didn't go over big around the police department.

An only child whose parents are retired civilian employes of the Navy Department. Hudson attended American University Law School at night while working as a deputy court clerk.

Before becoming commonwealth's attorney he served as chief assistant prosecutor for three years, a position Burroughs created and appointed Hudson to fill. Most recently, Hudson spent 18 months as an assistant federal prosecutor in Alexandria where he specialized in major drug cases.

"Henry is basically a street fighter in a Raleigh's suit," said Paul Murphy, a special assistant U.S. attorney who spent many 14-hour workdays closeted with Hudson building successful cases against international drug dealer Donald D. (Hillbilly) Haynie of Nashville and Alexandria massage parlor kingpin Louis MichaelParrish.

"I've met quicker studies, but Henry makes up for a lack of intellect by being incredibly hardworking," said Murphy, who recalled that Hudson would write down every question -- sometimes as many as 125 -- he planned to ask a witness.

"The thing that turns Henry on," Murphy said, "is vice -- seamier crimes like prostitution and drugs."

Hudson numbers the drug cases among his proudest accomplishments. In fact, the color photographs that adorn the walls of this office are of large bales of hashish seized in various raids. (A smaller picture of his wife Tara, a Marine Corps personnel analyst, and one of their terrier sit atop a bookcase.)

When asked about the drug photographs, Hudson, in a manner reminiscent of "Dragnet's" Sgt. Joe Friday rattles off the date, quantity, location and street value of drugs seized.

"I get a great deal of satisfaction from removing people from our community who prey on others," said Hudson as the police radio crackled in the background.

"I think that punishment is very much a part of the criminal justice system, but that doesn't mean everyone should go to jail," Hudson said. "I do think the citizens want burglars and dope dealers to go to jail and that's my view also."

Hudson adds that he will prosecute persons arrested for possession of small amounts of marijuana for personal use. "I've done a lot of studies about marijuana and I believe it is harmful," Hudson said, rocking back and forth in his high backed chair. "I don't think it enhances our society to have people walking around high on drugs."

Hudson's other priorities include the establishment of a special welfare fraud program, which he plans to set up in the next few months. Hudson said his staff is currently reviewing 10 such cases for possible misdemeanor indictments.

A man who says he never watches anything on television except the news, rarely reads anything other than newspapers or legal briefs, works six days a week and has followed the same nightly calisthenics routine for a decade, Hudson sees his chief weakness as the fact that he tires after working 10 hours.

"I think he's too serious and I told him that," said his father, Otis Hudson, in a telephone interview from his home in Orangeburg, S.c. "He's going to work himself to death.

"Henry was always very serious as a child, maybe too serious. He used to work in the firehouse as a volunteer on Saturday nights in high school. The only time I remember him getting into trouble was when he got a speeding ticket in college when he and some friends were on their way to Charles Town Race Track. I never saw him so scared," his father said.

While even his critics applaud his long hours and say he does a good job supervising the staff of eight assistants who they say frequently floundered under Burroughs, some say Hudson tends to be too rigid and coldblooded.

"It's been my experience with Henry as with many people who prosecute for a long time that they lose touch with ordinary people," said Marvin Miller, an Alexandria defense attorney who specializes in drug cases.

What bothers me about that is that a prosecutor is given such broad discretion about whether to prosecute a case or not. Henry has an undue respect for police and law enforcement agents and he believes jail is the cure for everything," Miller said.

"What we need are prosecutors interested in making real fundamental change rather than in using prisons to warehouse people or prosecuting kids for possesing a pound [of marijuana]," said Alexandria attorney William Moffitt. "Henry has a chance to do some very important things but he won't if he lets himself fall into the Horan mold."

At 33, Hudson is the same age Fairfax County prosecutor Robert F. Horan Jr. was when first elected commonwealth's attorney. Because of their convervatism, their extraordinary closeness to law enforcement agents, the two are often compared.

"Henry is very tenacious when it comes to catching bad guys," said Dave Green, a veteran Arlington detective who takes semiannual fishing trips with Hudson and a group of local police officers, lawyers and prosecutors known as "The Hookers."

"I think Henry is every bit as capable as Horan," said Green, who calls Hudson a perfectionist and a workaholic. "But Horan handles cases that get his name in the paper and Henry's not particularly interested in the press."

Friends say they believe Hudson's election represents the atainment of a methodically plotted career goal.

"I think being commonwealth's attorney is the only thing he ever really wanted in life and now he's got it," said Bob Holmes, an Arlington lawyer and long-time friend of Hudson. "Henry was lucky. He was in the right place at the right time and he won."

For his part, Hudson declines to speculate about any future plans, other than to say that he regards himself as a career prosecutor. Friends say he has told them he plans to run for reelection when his term expires in 1984.

"There's no issue that Henry is a competent lawyer," said Bill Dolan, an Arlington attorney and chairman of the criminal law section of the Virginia State Bar. "The issue is whether Henry is going to have the self-confidence and judgement to apply the law like an art."