The Laurel police chief said yesterday that Prince George's State's Attorney Jack B. Johnson told him he believed a highly publicized 1998 slaying of a Salvadoran immigrant in Laurel began as a robbery, despite Johnson's public statements that there was no clear motive.

"He told me that he agreed with [police] that the assault was not racially motivated and that robbery was the motivating factor for the attack," Laurel Police Chief Roy Gilmore said of the Nov. 10, 1998, telephone conversation with Johnson.

Later that day, Johnson announced he had dropped charges against four suspects, obtained indictments against three defendants and concluded that Laurel police were wrong in alleging the attack began as a robbery.

Gilmore described the conversation in an interview prior to a prayer vigil yesterday near the scene of the attack on Gilberto Hernandez, 40, and two of his brothers, Juan and Tomas. During the vigil, Johnson was sharply criticized by relatives of Hernandez, civil rights advocates and a prominent black Oxon Hill minister.

Gilmore, a former Prince George's County police official, said that he was reluctant to go public about their conversation because his department relies on the state's attorney's office to prosecute its cases but that he believes the public should know what Johnson said to him.

Gilmore said he took notes of the conversation and was surprised when the prosecutor later said robbery was not a motive. Gilmore said he spoke with Johnson two days later and Johnson told him he must have misunderstood their first talk.

Johnson, who has not spoken to reporters about the case for several months, did not return several phone calls seeking comment.

Initially, there was speculation that the assault by as many as seven black teenagers on three Salvadoran immigrants may have been racially motivated. Laurel police found no evidence of that, instead concluding it was a robbery attempt, based on statements by Juan Hernandez and one suspect.

Johnson has been sharply criticized by some Hispanic advocates and others for rejecting the robbery theory. His prosecutors did not actively present evidence of a robbery attempt during the recent trials of two defendants.

Defendants found to have killed someone during a robbery can be convicted of first-degree felony murder, which carries a possible life sentence. That's a much stiffer penalty than allowed for the charges for which two defendants were convicted--Cochise Iraun "Cody" Queen, 18, of involuntary manslaughter and two counts of second-degree assault; and Kelly Day Martin, 19, of three counts of second-degree assault.

Prosecutors, who did not present a motive during the Queen and Martin trials, argued for felony murder convictions in their closing arguments in both cases, after the judge ruled there was evidence of a robbery attempt. A third defendant was acquitted by a Circuit Court judge.

Queen tackled Hernandez and knocked him into the air, according to court testimony; the immigrant landed on his head and suffered a fractured skull. Prosecutors alleged that Martin caused a second skull fracture by kicking Hernandez in the head.

Hernandez died four days after the Sept. 4, 1998, assault.

Yesterday's prayer vigil took place in the Laurel apartment complex where the Hernandez brothers once lived. Led by the Rev. Brian Jordan, a Franciscan priest helping the Hernandez family, about 50 Hispanics carried placards accusing Johnson of insensitivity to Latino concerns.

"My family and I feel completely betrayed by the state's attorney's office," said Maria Hernandez, sister of the victims. "Prosecutors treated my brothers Juan and Tomas as if they were lying."

A spokesman for the Rev. C. Anthony Muse, pastor of Ark of Safety Christian Church in Oxon Hill, read a statement in which Muse said African Americans would feel the same anger Hispanics do if a white law enforcement official treated them the way Johnson has dealt with the Hernandez family.

"Justice was not afforded this immigrant by the state's attorney's office," said Ginny Gong, a member of Gov. Parris N. Glendening's Advisory Council on New Americans.

CAPTION: Cindy Hernandez, 9, niece of slaying victim Gilberto Hernandez, is held by her mother, Maria Hernandez, at a vigil near the site of the fatal attack on him.