Copyright 1988 The Times Mirror Company   Los Angeles Times November 24, 1988, Thursday, Valley Edition SECTION: Metro; Part 2; Page 14; Column 1 LENGTH: 203 words HEADLINE: DIGEST:  LOCAL NEWS IN BRIEF; WOMAN, 21, PLEADS NOT GUILTY IN DROWNING BODY: A 21-year-old Arleta woman, accused of participating in the killing of a teen-age girl, pleaded not guilty Wednesday to one count of murder in Glendale Municipal Court. Karen Severson is accused in the drowning of Michele (Missy) Avila, 17, in a creek in the Angeles National Forest on Oct. 1, 1985. A Pasadena Juvenile Court judge ruled Tuesday that Severson, 17 at the time of Avila's death, should stand trial as an adult. Severson and Laura Doyle, 21, were arrested on June 27 after authorities received information from a witness, Eva Chirumbolo. Chirumbolo testified at Doyle's preliminary hearing in Glendale Municipal Court on Friday that she accompanied Severson, Doyle and Avila to the forest but was not present when the drowning took place. Chirumbolo testified that Doyle admitted that she and Severson killed Avila because of an argument over Doyle's boyfriend. Avila's body was discovered by two hikers in a creek near Colby Canyon Road on Oct. 4, 1985. Doyle is scheduled to be arraigned in Pasadena Superior Court on Dec. 2. Severson is scheduled to appear for a preliminary hearing in the same court Jan. 24. If convicted, each woman could be sentenced to 25 years to life in prison.