Kellie Day Martin kicked Gilberto Hernandez as he lay unconscious from a hard tackle, a Prince George's County prosecutor alleged in her opening statement yesterday as Martin became the second teenager to go on trial for the highly publicized 1998 slaying of a Salvadoran immigrant in Laurel.

Sticking with a strategy that has drawn sharp criticism from some legal observers and advocates for Latinos, Assistant State's Attorney Fran Longwell offered no motive for the fatal attack on Gilberto Hernandez, just before one of her key witnesses testified yesterday that the assault began as a robbery. "It's a tragic case," Longwell said.

In his opening statement, one of Martin's attorneys, Assistant Public Defender John McKenna, seized on the prosecution's assertion that there was no clear motive for the attack, telling jurors, "You're not going to hear one satisfactory reason why Gilberto lost his life.

"What happened in this case was a tragic accident, a terrible mistake," McKenna added.

Prosecutors have alleged that Martin kicked Hernandez in the head, fracturing his skull. Longwell made no such assertion in her opening statement, and McKenna said the evidence will show that both skull fractures Hernandez suffered were caused when he hit the ground after being tackled. Martin kicked Hernandez in the forearm once or twice, McKenna said.

Martin, 19, is charged with first-degree murder and a slew of lesser crimes in connection with the assault on Hernandez, 40, and two of his brothers just before midnight on Sept. 4, 1998. The Hernandez brothers were attacked by five to seven teenagers as they returned home from their jobs at a nearby Route 1 restaurant.

Tomas Hernandez escaped his attackers on his bicycle and Juan Hernandez ran away, but Gilberto was tackled with such force that he was sent flying backward, hitting his head on a concrete sidewalk. He died in a hospital four days later, his skull fractured in two places.

Last month, a Prince George's County Circuit Court jury convicted Cochise Iraun "Cody" Queen, 18, of involuntary manslaughter and two counts of second-degree assault in the attack on the Hernandez brothers. Queen tackled Gilberto Hernandez, according to prosecutors and testimony at his trial. He has been sentenced to 15 years in prison.

Like Martin, Queen had been charged with premeditated first-degree murder, felony first-degree murder (a slaying committed in the commission of another crime, such as robbery), second-degree murder, manslaughter, involuntary manslaughter and assault.

A third defendant, Steven Darby, 17, is scheduled to go on trial Nov. 29.

State's Attorney Jack B. Johnson has said repeatedly that there is no credible evidence that the attack began as a robbery, though Laurel police concluded that it did. In their opening argument in the Queen case, prosecutors said there was no clear motive for the attack, then argued for a first-degree felony murder conviction after the judge ruled there was evidence for such a charge.

Circuit Court Judge E. Allen Shepherd threw out the premeditated first-degree murder charge against Queen but let stand the felony first-degree murder charge, citing the testimony of a witness who said he heard Martin suggest committing a robbery moments before the attack began.

That witness also is scheduled to testify against Martin.