Thomas A. Sweatt admitted in federal court yesterday that he is the serial arsonist who struck dozens of Washington area homes and apartments in the hours before dawn, acknowledging that he kept setting fires even after two of his blazes killed elderly women.

For the first time, prosecutors tied Sweatt to a fire in February 2002 that killed an 89-year-old woman in Northeast Washington. Sweatt admitted that crime after authorities found a newspaper clipping about the fire in a search of his Southeast Washington apartment. The victim, Annie Brown, died of smoke inhalation.

New details also emerged about a June 2003 fire that took the life of an 86-year-old woman in Northeast Washington. Like the other places he struck, Sweatt chose the home of Lou Edna Jones at random, prosecutors said. He sat on her front porch for about 15 minutes "getting his nerve up," they said, even admiring its appearance. Then he struck. The fire killed the widow in her home of 50 years. Like Brown, Jones died of smoke inhalation.

A former fast-food restaurant manager, Sweatt pleaded guilty to arson and murder charges less than six weeks after his arrest, a remarkably quick resolution for a criminal case. Sweatt, 50, sometimes appeared near tears as prosecutors chronicled a wave of fires that terrorized neighborhoods in Maryland, the District and Virginia.

Sweatt gave no explanation for the fires, and it remains a mystery why he set them. Prosecutors have quoted him as saying he was driven by demons and addicted to setting fires. Sweatt set 33 more fires after the one that killed Jones, according to his guilty plea. The fires injured several people and caused millions of dollars in damage.

All told, Sweatt took responsibility for 45 fires and one attempted arson. He said little during the hearing in U.S. District Court in Greenbelt. He will be sentenced Sept. 12, and his plea agreement calls for a life prison term.

Dressed in a bright orange jail jumpsuit, Sweatt pleaded guilty to 13 arson counts and two counts of murder. The plea agreement was signed by federal prosecutors in Maryland, Virginia and the District. Sweatt secretly signed it May 10, and the court kept it under seal until yesterday's hearing.

U.S. District Judge Deborah K. Chasanow reviewed the charges with Sweatt as a dozen victims, relatives and friends watched the proceedings, along with about a half-dozen of Sweatt's relatives and acquaintances.

"Justice has been served," said Darlene Lloyd, Jones's daughter. "Life without parole, what more could you ask for?"

She added, "It really hurt me to hear this man sat on my mother's porch for 15 minutes before he set the house on fire."

Sweatt, of the 500 block of Lebaum Street SE, has been jailed since his arrest April 27. Authorities said they tied him to the fires through DNA evidence recovered at four of the arsons. Within hours of his arrest, they said, Sweatt admitted the crimes.

Investigators have said they believe Sweatt may have identified targets -- at least initially -- while driving co-workers home after his shift ended about midnight at a KFC/Pizza Hut restaurant at Bladensburg Road and New York Avenue in Northeast Washington.

Sweatt used plastic containers filled with gasoline to set the fires, according to the plea agreement. He typically placed a wick -- such as a piece of fabric -- at the end of the container and lighted it, allowing himself time to flee before the crude incendiary device exploded, authorities said.

Of the 45 fires, Sweatt admitted setting 21 and attempting to set another one in the District. He admitted setting 19 in Maryland and five in Virginia.

Prosecutors said the guilty pleas were a good resolution to the case. There is no parole in the federal system, and Sweatt has agreed to give authorities an "off-the-record" debriefing on any lingering questions about the fires.

"I hope today marks another step in the healing process for the victims and their families and that the citizens of our communities feel a sense of relief that the serial arsonist has been found, convicted, and will spend the rest of his life behind bars," said Allen F. Loucks, U.S. attorney for Maryland.

Sweatt's attorney, Assistant Public Defender John C. Chamble, struck a similar tone about the need to move forward. "This is the first step in a healing process for the victims and their families, as well as Mr. Sweatt and his family," he said.

Sweatt pleaded guilty to first-degree murder while armed in the fire that caused Jones's death and second-degree murder while armed in the fire that killed Brown. The fire that killed Brown was not on a list of suspected arsons that authorities publicized throughout the investigation. They previously believed that the attacks began in March 2003.

Brown's rowhouse, in the 1200 block of Montello Avenue NE, caught fire Feb. 5, 2002, after flames spread from an adjoining house that Sweatt had ignited. More than three years later, the rowhouse remains vacant and damaged, its windows broken and boarded up.

Lanita Huff, 32, a public school teaching assistant who lives around the corner, said she was stunned and relieved by the revelation that Sweatt set the fire. The heat generated by the fire that night was so intense, she recalled, that it awakened her two small children.

"Oh my God, oh wow," Huff said of the guilty plea. "He hurt a lot of people. He put fear into a lot people's hearts."

At the courthouse, the victims included Ida Collins-McCoy, who was sleeping when Sweatt struck her Northeast Washington house in November 2003. After suffering from nightmares and many sleepless nights, she said she wanted to see Sweatt in person.

"I think he's a very sick man," Collins-McCoy said.

Also in court was Jean Kyler, whose mother, Anita Kyler, suffered smoke inhalation in a March 2003 fire in Northeast Washington. She said she wanted to learn what drove Sweatt to act and why her mother had become a victim.

"I was just so mad about the whole situation," she said. "Why did he do this? What were his reasons? I still don't know."

Staff writer Paul Schwartzman and staff researcher Bobbye Pratt contributed to this report.

Sisters of Thomas A. Sweatt walk with a defense attorney to the federal courthouse in Greenbelt. A half-dozen relatives and acquaintances attended.

Sweatt shows emotion as the details of one of his crimes are read in court before he pleads guilty.

Jean Kyler was among the relatives and friends of victims at the hearing. Her mother's house was one of those set on fire.