An amusement park employee with a background in pyrotechnics was the ringleader in a $10 million arson spree at a suburban Washington housing development, a federal prosecutor said Thursday.

Prosecutor Donna Sanger said at a hearing that Patrick Walsh (search), 21, was the "instigator" of the plot and the leader of a tightly organized group of young men who referred to themselves as The Family and set the fires to make a statement.

A federal magistrate ordered Walsh held without bail.

Six young men in all have charged in the Dec. 6 string of fires that destroyed 10 houses and damaged 16 others at the Hunters Brooke (search) community, an upscale development under construction.

"He had this fascination with fire and he focused on the Hunters Brooke development as the place where he wanted to make this statement," Sanger said in court. "He is the one who settled on the means, the method and the target."

She said Walsh may have been responsible for other fires, including one set in a field in Prince George's County. Sanger said Walsh had a background in pyrotechnics; she would not elaborate.

William Purpura, Walsh's attorney, said his client worked a summer job at Six Flags Amusement Park (search), but added: "He has absolutely no expertise in pyrotechnics."

Purpura also said there was no such thing as The Family. He said Walsh was part of a group of friends with a shared interest in cars.

In court papers, investigators have offered various possible motives for the fires, including revenge against the builder and the security company at the construction site; racism (the defendants are white, and many of the homeowners are black; and a quest for notoriety for The Family, which prosecutors said was also known as the Unseen Cavaliers.

Also Thursday, Sanger told the court that suspect Roy T. McCann Jr., 21, knew of the fires in advance and drove to the development to take part in the arson. McCann's attorney, Joshua Treem, said the young man only watched the fires.

"Mr. McCann has been swept up in this," Treem said.

The federal magistrate ordered McCann released on home detention while he awaits trial.

Prosecutors also obtained eight search warrants Wednesday that were placed under seal. According to court records, authorities sought to search computers, cell phones and homes of some of the suspects. Purpura said the home of Walsh's parents was searched Wednesday night.