HOUSTON—A woman and her boyfriend were arrested Tuesday in the death of the woman’s 8-year-old son, whose skeletal remains were found inside a Houston-area apartment with three surviving but apparently abandoned siblings, officials said. Brian W. Coulter, the 31-year-old boyfriend of the dead child’s mother, was charged Tuesday with murder. The mother, Gloria Y. Williams, 35, was charged with felony injury to a child by omission, and tampering with evidence (human corpse), Harris County Sheriff Ed Gonzalez tweeted Tuesday night. Both were booked into the Harris County Jail without bond pending appearances before a magistrate. It was not immediately clear if the two had attorneys. Gonzalez said more charges are possible. The Harris County Institute of Forensic Sciences in Houston, which conducts all autopsies in the county, listed the primary cause of death as “homicidal violence with multiple blunt force injuries.” Michele Arnold, a spokeswoman for the institute, said her …