A Gaithersburg woman who said she was led astray by an ex-convict working as a dating service salesman was found guilty yesterday of solicitation to murder and maim her ex-husband, after just 30 minutes of deliberation by a Montgomery County Circuit Court jury.

Ruth Betty Blosser, 50, left the courtroom in tears after Judge Richard Latham allowed her to remain free on bond until she is sentenced May 3. She could receive 40 years to life in prison for the two offenses.

Prosecutor John McCarthy told jurors yesterday morning that Blosser, who had been divorced six months, asked a representative from a Laurel computer dating service who came to her apartment last March to kill her ex-husband in Ohio for $5,000.

The two had sex, McCarthy said, but the dating service representative then went to county police. Police sent the man, wired with a microphone, to Blosser's apartment Aug. 12. While police listened outside the apartment, McCarthy said, the man was given three rings to kill or maim Blosser's ex-husband.

Blosser, a temporary secretary, testified yesterday morning that she had no intention of killing her ex-husband, a hospital administrator in Ohio. She said the dating service representative, Vincent Michael McCarthy (no relation to the prosecutor), seemed eager to kill him to earn some money.

When the man proposed murdering her husband, she said, "I couldn't believe it . . . . The thought had never occurred to me." She said she did suggest to the man ways in which her husband could be killed. "I went into detail about a way that he could do it -- as a joke," she said.

During their telephone conversations, she said, "he kept pushing me, and kept pushing me . . . . He solicited me." During their last meeting, she said, she gave him the rings only so that he could get them appraised, not as partial payment for a killing.

Defense attorney Joseph DePaul called Blosser a "poor, foolish lonely woman" and painted Vincent McCarthy as the true villain. He described Vincent McCarthy, who has a long criminal record, as a "career hood, a con man and a common criminal" who was trying to get off parole for a 1977 bank fraud conviction.

He said Blosser had been beaten and cheated out of money by her ex-husband and was in emotional distress, while Vincent McCarthy was "an opportunist who seized this opportunity." He accused police of doctoring tape recordings of Blosser's conversations with Vincent McCarthy and composing a statement she gave police after her arrest.

John McCarthy called Blosser's explanation of the incident "amazing."