Three of the four teens charged with the robbery and murder of a Beersheba Street man last month have been transferred from juvenile court and will now be tried as adults.Meanwhile, Sam Brinkley, the teen prosecutors say was the trigger man who opened fire and killed Oswaldo Luna, 43, with an assault rifle while the victim slept in his bed, was the only one of the 17-year-olds not transferred following Thursday’s closed hearing. Brinkley’s transfer will be delayed while he undergoes a mental evaluation. Once that evaluation is complete, he could join his fellow alleged teen conspirators, Charles Guess, Malik Scott and Melvin Horn in being transferred to adult court.