A member of the violent Mara Salvatrucha gang admitted yesterday to participating in a machete attack last May that mutilated the hands of an Alexandria teenager, a crime that heightened concerns about gangs in the Washington area.

Hayner R. "Rolando" Flores, 18, of Annandale pleaded guilty in Fairfax Circuit Court to malicious wounding and illegal participation in a street gang, rather than face a more serious charge of aggravated malicious wounding. The latter crime could have resulted in a life sentence; instead, he faces a maximum of 30 years in prison.

Flores and two other members of the gang, also known as MS-13, attacked the 16-year-old after a confrontation with his gang, the South Side Locos, according to prosecutors. The victim lost four fingers and suffered deep cuts to his head and back. The attack shocked the public and prompted officials to pledge more money and efforts to contain gang violence.

Flores' attorney, Gary M. Greenbaum, emphasized that his client was not the one who severed the victim's fingers -- an act that became symbolic of gang brutality. Flores had agreed to plead guilty to the same charges in July but backed out.

Flores "is not a poster child for gang violence, like he's been depicted to be," Greenbaum said, blaming the slashing on other gang members. But the victim's mother said the assault had ruined the dreams of her son, who had hoped to be a mechanic.

"What can I say? I feel like I'm a person who has lost everything," his mother said yesterday in a phone interview. "I live what they did on May 10, I live it every day," said the woman, who spoke on condition of anonymity.

The attack grew out of a rivalry between the two largest Latino gangs in Northern Virginia, according to an account provided in court by Assistant Commonwealth's Attorney Jay R. Nanavati.

He said that on the night of the assault, Flores and two other members of Mara Salvatrucha were walking to a convenience store when some young women approached in a white car, yelling their support for the South Side Locos. Flores' friend Cristobal Z. Medrano cursed and tossed a bottle at the car, the prosecutor said.

A few minutes later, the car returned. This time, several gang members were in the vehicle, including the future victim, who was brandishing a baseball bat emblazoned with the South Side Locos name, the prosecutor said. The bat-wielding youth and other gang members chased Flores and his friends, who ducked into an apartment and picked up machetes, the prosecutor said.

They then set off in pursuit of the South Side Locos group, catching the victim about 1 a.m. along Edsall Road, east of Interstate 395, and knocking him down, the prosecutor said. The three assailants began chopping at the victim's head and back, slashing his hands as he tried to defend himself, the prosecutor said. The three young men finally took off, "leaving the victim for dead," Nanavati said.

Medrano, of Alexandria, also has pleaded guilty to malicious wounding and participation in a street gang. The third man accused in the case, Jose Cruz, 19, has pleaded guilty to charges of malicious wounding by a mob and gang membership.

Flores, who immigrated to the United States three years ago and briefly attended Annandale High School, had initially denied to police that he was present during the attack.

But he later changed his story. He agreed to plead guilty on July 28 to malicious wounding, which has a maximum sentence of 20 years, and gang participation, which carries a maximum of 10. When he got to court that day, however, he abruptly declared that he would not accept the gang charge.

Greenbaum, his attorney, said Flores had simply gotten confused because authorities had told him they wouldn't pursue gang charges in a separate case, in which he is accused of damaging public property by carving "MS-13" into his cell window.

Yesterday, Flores answered "Si" in a soft voice as Judge Dennis J. Smith asked if he understood the plea agreement and had decided to plead guilty. Flores appeared in a baggy green prison uniform, his shoulders slumped.

Sentencing for Flores is scheduled for Nov. 19. His attorney said that, under state sentencing guidelines, Flores could receive about nine years in jail. But Greenbaum said that he would argue that Flores deserved less, since the victim was a gang member who had tried to harm Flores and his friends.

"This was the result of a fight" rather than an assault on an innocent bystander, he said. The prosecutor said the victim had a tattoo on his stomach with his gang nickname, Droopy.

The victim's mother said that even if there had been a confrontation, Flores had done a terrible thing.

"It doesn't give him the right to destroy a body," she said.