A superior court judge sentenced "gangsta" rap mogul Marion "Suge" Knight to nine years in prison today, telling him, "You blew it," when the controversial music executive violated probation by participating in an attack on a gang member last September.

Judge Stephen Czuleger delivered a stern lecture in sentencing the 31-year-old Knight, saying that his violent history made him a risk to society.

"I was, to be honest, hoping you'd say, I really blew it. I got involved in this attack on this guy. I can't believe how stupid I was,' " Czuleger said in a packed Los Angeles courtroom as Knight listened impassively. "You didn't. You said, The crime I'm on probation for I didn't commit.' You weren't completely honest on the stand, and now you say, You can trust me, judge.' " He added, "I gave you every benefit of the doubt, and I have to say you did blow it. You haven't accepted responsibility for your actions."

The owner of rap music's most successful company, Death Row Records, Knight was on probation from a 1992 felony conviction on two counts of assault with a firearm. He had pleaded guilty to the assault charges under an agreement that gave him a nine-year suspended sentence. The probation violation occurred when Knight was seen with other Death Row employees kicking and punching Orlando Anderson in Las Vegas on the night rap star Tupac Shakur was fatally shot.

The sentencing marks a nadir for the successful executive, who in a matter of months has gone from being rap music's most influential force to being jailed, investigated by the FBI, Drug Enforcement Administration and IRS and sued by a former colleague and creditors, including American Express. Knight lost one of his premier stars with the death of Shakur, and published reports suggest that his other major star, Snoop Doggy Dogg, may defect to another recording label. However, the label continues to be phenomenally successful, largely on the strength of Shakur's posthumous recording and Snoop Doggy Dogg's most recent CD.

Just before being sentenced today, Knight, dressed in prison blues, gave a rambling, 20-minute speech in which he protested that although he kicked Anderson he did not deserve jail. "I admit I was frustrated . . . but at the same time, it's not a nine-year kick," he said. Knight added that he did not instigate the aggression that resulted in the first conviction -- two brothers accused him of threatening them with a firearm if they did not join Death Row -- and said that he had been "treated like a wild animal" in jail.

Knight's supporters filled the courtroom today, some wearing T-shirts with his face emblazoned on it, most wearing yellow ribbons. Some of the label's singers said they would stick with Death Row even with Knight in prison. "I'm at Death Row till the world blows up," said Danny B, a rhythm and blues singer. "Suge Knight is the brain of Death Row but we are the thoughts. Death Row will be moving on."

Defense attorney David Kenner said he would immediately appeal what he called an "inappropriate" sentence, adding that Knight would continue to "set the course and direction" of the record label from jail. Kenner and five other lawyers argued vehemently all day that Knight did not deserve nine years in jail for what they called a relatively minor violation, and emphasized that despite his previous convictions, he had not violated probation in the previous five years.

Knight's misfortunes date back to the weekend of Sept. 7, when he and members of Death Row Records went to Las Vegas to attend the boxing match between Mike Tyson and Bruce Seldon. Knight, a 335-pound former football player, was recorded on a video surveillance tape at the MGM Grand Hotel along with Shakur and members of their entourage punching and kicking Anderson after the match.

Shakur was gunned down a few hours later in a drive-by shooting as he and Knight waited at a traffic light. Knight was driving the car and sustained minor injuries. Police have not arrested or charged anyone in the killing, but have accused Knight of refusing to cooperate with their investigation. Anderson, whom police consider a suspect, has declined to press charges over the assault.

Knight's case has further highlighted the often-violent lifestyle of hard-core rap figures. Knight has a long list of convictions, including battery, assault with a deadly weapon and a federal weapons possession charge; Shakur also had several convictions before his murder, and Snoop Doggy Dogg was acquitted of murder charges last year.

Rap music, which sells millions of records each year, is criticized by conservative opponents as condoning violence, racism and sexism. One of the most outspoken opponents, C. DeLores Tucker, attended Knight's sentencing today, telling reporters that she was sad because she believed he was willing to change.

Witnesses from three nonprofit organizations pleaded with the judge to put Knight back on probation rather than send him to jail, saying that he had promised to become active in their job-training and community-based activities.

But Czuleger appeared unconvinced by their arguments, although he gave Knight credit for 375 days already served in jail. He denied a half-dozen motions by Knight's attorneys seeking to delay or dismiss the probation sentencing. Kenner had asked that the case against Knight be thrown out, saying that a Las Vegas detective deliberately lied under oath regarding Knight's participation in the assault. Another motion maintained that prosecutors had secured the plea bargain by making false promises to Knight.

Defense lawyer Richard Hirsch called a psychiatrist, Michael Coburn, to the stand as an expert witness to dispute the findings of prison staff that Knight is a threat to society. "Their wording implies that he's an ongoing thug, that he's an ongoing violent person, and that's not true," Coburn said.

But Deputy District Attorney William Hodgman pointed out that Knight had been granted probation four previous times, once for battery. "How many bites of the probation apple does this defendant get?" he asked.

The case against Knight was further complicated by an investigation into the allegedly improper ties to Death Row of the district attorney who negotiated Knight's plea bargain. Lawrence Longo, who was dismissed earlier this month, rented his Malibu home to Death Row attorney David Kenner, and Knight lived there last summer. Knight also gave a recording contract to the prosecutor's 18-year-old daughter, Gina, the only white musician signed to the label. Death Row Records is also under investigation by the FBI for possible connections to criminal activity. American Express brought a suit in January against Knight, Kenner and Death Row, seeking payment of $1.5 million owed to the credit-card company. And in a recent article in the local LA Weekly newspaper, convicted cocaine dealer Michael Harris -- one of the most powerful figures on the crack cocaine scene of the 1980s -- claims that he provided $1.5 million in seed money to launch Death Row. CAPTION: Marion "Suge" Knight and his attorney David Chesnoff in court in Los Angeles yesterday. CAPTION: Protester pickets the Los Angeles Criminal Courts Building yesterday, where rap mogul Marion "Suge" Knight received a nine-year prison sentence.