PORT-AU-PRINCE — The Obama administration expressed concern on Monday over the speed of a court ruling in Haiti that dropped charges against a man accused in a kidnapping ring who had close ties to the family of President Michel Martelly.

On Friday, the judge freed Woodly Ethéart, who has known Mr. Martelly since they both worked in the music business, and Renel Nelfort. Mr. Ethéart and Mr. Nelfort are suspected of being the leaders of the Galil Gang, and they were indicted in March on charges of masterminding a host of violent crimes, including murder, money laundering and more than a dozen kidnappings.

Shortly after the indictments were announced, the minister of justice dismissed the prosecutor, saying his deputies had asked the judge to free the men because they did not think that they could win a conviction.

“We are concerned about the ruling, including the speed in which it was made,” a State Department spokesman said in an email on Monday in response to a request for comment. “This is an ongoing case in the Haitian courts, and we understand the ruling could be appealed.”

Mr. Ethéart, a former music promoter, is a friend of Martelly’s brother-in-law, Charles Saint-Rémy, and his family owns La Souvenance, a French restaurant where the president often dines.

Critics say that the president has surrounded himself with a network of friends and associates who have been arrested or figured in criminal investigations.

“The prosecutor in Port-au-Prince was removed because the government was not satisfied with the performance at the trial,” Péguy Jean, a spokesman for the Ministry of Justice, said on Monday. “At the end of the trial, the prosecutors asked the charges to be dropped.”

Mr. Martelly’s spokesman did not respond to a request for comment.