Jeremy D. Parady, 20, of Accokeek, pleaded guilty to one count of conspiracy to commit arson at a rearraignment in U.S. District Court in Greenbelt.
''The defendant, Jeremy D. Parady, selected or aided and abetted the selection of the Hunters Brooke development as the object of the arson because he knew or perceived that many of the purchasers of the houses in that development were African-American,'' Assistant U.S. Attorney Donna Sanger said.
Prosecutors planned to seek a sentence of nearly 10 years in prison and restitution of $4.18 million, according to a plea agreement.
Parady was one of five men charged in the fires in December at the Hunters Brooke subdivision in Indian Head. Many of the residents who planned to move to the development were black, while all the suspects are white. Indian Head is in Charles County, a formerly rural area of Charles County that is rapidly becoming a suburb of Washington, D.C.
All five men were charged with arson, conspiracy to commit arson and aiding and abetting; none was charged with committing a hate crime.
The fires did an estimated $10 million in damage. No one was hurt.
Parady's role in setting the fires was to drive one of the cars the suspects used to travel from house to house as they lit the blazes, Sanger said. He also supplied some of the flares used to start the fires, she said, taking them from a volunteer fire company in Accokeek where he was a firefighter.
Parady also recruited or attempted to recruit other people to take part in the conspiracy, Sanger said.
Parady said little in court, answering ''yes'' or ''no'' to questions from Judge Roger Titus. He wore a green prison jumpsuit and was led away in handcuffs.
Parady's sentencing is set for June 14.
In addition to racism, other possible motives for the fires have been presented by prosecutors and in court filings, including a desire by alleged ringleader Patrick Walsh to gain fame for a loosely organized group called ''the family.''
There was early speculation that the fires were set because environmentalists had deemed the upscale houses a threat to a nearby bog. But authorities later said no evidence was found to support that theory.
