One of three teenagers charged in connection with the 2020 arson that killed five members of a Senegalese family in Denver’s Green Valley Ranch neighborhood has pleaded guilty to second-degree murder in the case, court records show. Dillon Siebert, 17, on Wednesday will be sentenced for his role in the deaths of Djibril Diol, 29; Adja Diol, 23; Khadija Diol,