LAS CRUCES, N.M. (KVIA) -- A New Mexico district judge ruled to keep a murder conviction of the first defendant tried in the Young Park mass shooting Thursday. Tomas Rivas was found guilty of three counts of first degree murder in the shooting. His attorney asked the court for a retrial after learning about allegations a juror communicated with someone outside the panel during the murder trial, documents said. During Thursday's hearing, the dist…