PHILADELPHIA - Kentucky Derby winning jockey Stewart Elliott was on his way back from an overseas trip when his past caught up with him again.

Elliott, a Canadian citizen who won the Derby and Preakness aboard Smarty Jones last year, was taken into custody Tuesday and detained by customs agents in connection with a guilty plea to felony assault four years ago, the Department of Homeland Security said Wednesday.

The 40-year-old Toronto native was returning from a trip to Hong Kong late last year when federal agents interviewed him at John F. Kennedy International Airport in New York, but let him go on his way, said Homeland Security spokesman Manny Van Pelt.

He was asked to return to a Customs and Border Protection office in New York, where officials said he was arrested and transferred to Immigration and Customs Enforcement in Philadelphia.

Elliott was held at the York County Prison in central Pennsylvania. He was released shortly after 5 p.m. Wednesday, said Kelly Wietsma, a spokeswoman for Elliott. The jockey was expected to appear before a federal judge Thursday.

"This was an unfortunate situation. The arrest was many years ago. I served my probation and paid the fine," Elliott said in statement released by Wietsma. "I thought this was all behind me."

Elliott's criminal history become public during Smarty Jones' bid for the Triple Crown, which fell short when he lost to Birdstone by a length at the Belmont Stakes in June. But federal officials said they weren't aware of it until recently.

"It takes time for court records to get entered," Van Pelt said Wednesday. "There are tens of thousands of convictions that occur in the United States every year."

Under federal immigration law, aliens with felony convictions are subject to removal from the United States. Van Pelt declined to comment on Elliott's immigration status specifically, but said that he "is not here illegally."

A lawyer for Elliott said her client voluntarily appeared before the immigration court Tuesday.

"Mr. Elliott voluntarily appeared before the immigration court in Philadelphia on March 1 to address the 2001 incident that was made public after the Kentucky Derby," Supti Bhattacharya, a lawyer representing Elliott, said Wednesday from her office in Trenton, N.J. "The current situation is merely a procedural issue and will be resolved within the next 24 hours."

Elliott pleaded guilty in June 2001 to aggravated assault stemming from a fight with a friend inside the man's Burlington County, N.J., home in 2000. He was sentenced to one year of probation and ordered to pay $13,900 to cover the victim's medical bills, according to court records.

Elliott beat Alexander Kovakik with a beer bottle, pool cue and wooden stool, according to the grand jury indictment charging the jockey with aggravated assault, possession of a weapon and unlawful possession. The latter two charges were dropped after Elliott agreed to plead guilty.

In April 2002, a judge cut short Elliott's probation by two months after his lawyer said New Jersey racing officials would not renew his jockey's license.