A former teacher serving more than 100 years in prison for the rape and abuse of the daughter of a woman who vanished nearly two decades ago has been found dead in his jail cell one day after he was named a person of interest in the woman's disappearance, according to officials.

Montgomery County police said Fernando Asturizaga was found dead in his jail cell Thursday evening. Authorities said officers found Asturizaga unresponsive in his cell at about 8:45 p.m. and he was pronounced dead at the scene. Detectives are investigating Asturizaga's death and said the disappearance case of Alison Thresher continues to be an open and ongoing homicide investigation.

Preliminary evidence indicates Asturizaga killed himself but his official cause of death will be determined by the medical examiner, according to authorities.

Asturizaga was sentenced to 128 years in prison for raping Alison Thresher's daughter, Hannah Thresher, for three years, beginning when she was 10 years old. Montgomery County Police Chief Thomas Manger said that prior to her disappearance, Alison Thresher told Asturizaga, her estranged husband, and her daughter's school that she did not want Asturizaga to have contact with her daughter any longer.

Officials said on Thursday that they believed Alison Thresher was killed in her apartment and her body was taken to an unknown location. Following Asturizaga's sentence in 2012, Alison Thresher's case was reopened.

"Based on forensic analysis, we now believe the suspect attempted to destroy evidence at the time that the crime was committed inside her apartment," Manger explained on Thursday.