LOS ANGELES—An ex-convict was found guilty on March 10 of the murder of an 11-year-old boy who was kidnapped more than three decades ago while walking home from school in Inglewood. A downtown Los Angeles jury deliberated about three hours before convicting Edward Donell Thomas, 53, of Pomona, of first-degree murder for the May 24, 1990, death of William Tillett. Jurors also found true the special circumstance allegation of murder during the commission of a kidnapping, but could not unanimously agree on a second special circumstance allegation—murder while lying in wait. In California law, a murder case with a special circumstances allegation—which makes the case a more serious kind of first-degree murder—can lead to either capital punishment or life in prison without the possibility of parole. The boy was kidnapped just before 3 p.m. that day in the area of Imperial Highway and Crenshaw Boulevard while walking home from Kew …