Mark Phillips's 4-year-old daughter had been kidnapped by his estranged wife, and the Alexandria man did what any good detective would do: He called his wife's close friend.

Phillips wanted to know whether his wife and her boyfriend had ever talked about going anywhere. Yes, the friend replied. They had mentioned they might want to move to the small Spanish island of Ibiza.

From that clue, Phillips launched a personal mission to find his daughter, Avalon. Frustrated with the police and the FBI, the former British Royal Marine commander flew to the Mediterranean island. He drove the streets for 10 days, handed out fliers and scoured playgrounds.

Hours from giving up, Phillips spotted Avalon in a phone booth near a McDonald's with his wife's boyfriend. He screeched his car to a halt, grabbed his daughter and flew home with her to Northern Virginia.

Yesterday, Phillips watched with barely concealed satisfaction as an Alexandria judge sentenced his now-former wife, Amy Boggio, to two months in prison for the 2000 kidnapping. After nearly five years as a fugitive, Boggio returned to the United States in March and was arrested at Dulles International Airport. She pleaded guilty in April in Alexandria Circuit Court to a charge of kidnapping in violation of a custody or visitation order.

"I think this sends a message to other parents and abductors that there are consequences to face," said Phillips, 38, who lives in Alexandria with Avalon, now 9.

Judge Lisa B. Kemler told Boggio -- who violated a court order when she failed to return Avalon to her father over Easter weekend in 2000 -- that she had put her daughter at "great risk."

Boggio, 34, shook during a brief statement to the judge that was mostly inaudible. She said she never meant to hurt her daughter or Phillips. Her father, Joe Boggio of Burke, said after the hearing that Boggio is "very regretful" and "devastated" that she has not seen her daughter in more than five years. She has been barred from seeing Avalon since she returned to the United States.

Alexandria police said they understood why Phillips took the unusual step of flying halfway around the world to get his daughter back.

"Obviously we don't encourage anyone taking the law into their own hands or completing their own investigation," said Capt. John Crawford, a police spokesman. "But when you're talking about a parental abduction, emotions are running very high."

Crawford rejected Phillips's contention that police failed to aggressively investigate Avalon's disappearance. "Our detective was very thorough, and she stayed on top of this case throughout," he said.

Debbie Weierman, an FBI spokeswoman, said that although she was unfamiliar with the case, "there are specific criteria which must be met before the FBI is able to open an investigation." She also warned that people who personally investigate criminal cases "should be aware of the danger or complications that may arise."

Phillips and Boggio, who sat on opposite ends of the courtroom yesterday and did not speak, were married in 1996 in England. By 2000, they were in divorce proceedings and had joint custody of Avalon. Boggio had taken Avalon for Easter weekend.

On Easter Sunday, Boggio's father called Phillips.

"He told me that one of Amy's closest friends had called him and said she had left the state, possibly the country and had no intention of returning," Phillips recalled.

Phillips put his innate detective skills to work. He called a friend in England and learned that the friend had sent Boggio a duplicate of Avalon's birth certificate. Then he called the friend of Boggio's who said she wanted to move to Ibiza, part of an island chain about 100 miles south of Barcelona.

Phillips and Boggio had first met on one of the islands in 1994, when Phillips owned a bar there. He now sells cars at an Arlington Porsche dealership. After other clues pointed to Ibiza, Phillips flew there in late July 2000.

He had no luck until he happened to spot Avalon in the phone booth. He threw his wife's boyfriend to the ground and took Avalon, who had been in the boyfriend's arms.

"I said, 'Hey baby, here you go. . . . I'm going to take you home now,' " Phillips recalled. "She was obviously a little confused, but she was happy to see me."

At yesterday's hearing, Phillips testified that Avalon woke up screaming in the night for the next six months but is now an honor student who plays the violin. "She's a very happy child," he said in an interview.

Boggio's attorney, Lance D. Gardner, told the judge that Boggio fled because she was worried that Avalon was abused by Phillips's roommate.

Phillips called the abuse allegation "a total fabrication."

Gardner said later that Boggio had always intended to return.

Assistant Commonwealth's Attorney Shelby Hadfield urged Kemler to sentence Boggio to a year in prison, calling the kidnapping carefully planned. "The defendant seeks pity, but I'll remind your honor that she is not the victim. Avalon and her father are," Hadfield said.

Mark Phillips with his daughter, Avalon, 9, in their Alexandria home. Avalon's mother, Amy Boggio, was sentenced to two months in prison."I think this sends a message to other parents and abductors that there are consequences to face," said Mark Phillips, with daughter Avalon.