Fernando Asturizaga Credit: Via Montgomery County police

A man named as a “person of interest” Thursday afternoon by Montgomery County detectives in connection to a Bethesda homicide from nearly 18 years ago was found dead hours later in his prison cell.

A correctional officer at Western Correctional Institution in Cumberland found Fernando Asturizaga, 51, unresponsive at 8:45 p.m., and he was pronounced dead. Law enforcement officials are conducting a death investigation.

Asturizaga was the focus of a renewed effort of a homicide investigation that has been unsolved since May 2000, when Bethesda woman Alison Thresher, then 45, disappeared from her home.  She was initially considered missing, though police now think she was killed in her apartment. Her body has never been found.

Police don’t know exactly what happened to her, but they know that she was catching on Asturizaga’s abuse of her then 11-year-old daughter. Asturizaga was serving a sentence of more than 160 years for rape and abuse of Hannah Thresher when he was found dead.

[Related: County Police Revisit Cold Case of Missing Bethesda Woman, Seeking Information About Man Who Abused Her Young Daughter]

Police said Friday that the investigation into the disappearance and death of Alison Thresher remains open. Her family did not want to comment further publicly.

Alison Thresher. Via Montgomery County police