Kentucky Derby (search) winning jockey Stewart Elliott (search) has been arrested and detained by federal immigration officials because of a guilty plea to felony assault four years ago.

Elliott, a Canadian citizen who won the Derby and Preakness aboard Smarty Jones (search) last year, was taken into custody Tuesday and arrested by U.S. Immigrations and Customs Enforcement agents at the Philadelphia International Airport, the Department of Homeland Security said in a statement.

The 39-year-old Toronto native was being held Wednesday at the York County Prison.

Elliott's criminal history become public during Smarty Jones' bid for the Triple Crown (search), which fell short when he lost to Birdstone by a length at the Belmont Stakes (search) in June. It then showed up in screenings by customs officers at the Philadelphia airport this week, Homeland Security spokesman Manny Van Pelt said.

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."

Unless Stewart agrees to leave the country, he will remain in detention until a federal immigration judge determines his status, officials said.

A lawyer for Elliott said her client voluntarily appeared before the immigration court Tuesday and believes the matter will be resolved Thursday.

"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 procedure 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.