A heretofore secret witness--previously described as a jailhouse snitch--testified in the murder trial of Cesar Rodriguez, charged with killing his 7-year-old stepdaughter Nixzmary Brown in 2006. The witness claimed the girl's mother confessed to killing her daughter. Nixzaliz Santiago, Nixzmary's mother who will face her own murder trial later, allegedly told the witness that Nixzmary was a bad child and she and Rodriguez beat the young girl in the bathtub. She testified that Santiago "kept......