CASTRO VALLEY — Five months since the mysterious brutal killing of a 59-year-old optician, the Alameda County District Attorney has charged a man with her murder and torture.

Andrea St. John’s charred remains were found in the garage of her Castro Valley home on Grove Way on Dec, 13, 2016. Investigators at the time believed she did not die in the flames, and her killer remained at large until recently. On Friday, the DA’s office charged Luckie Dacany, 36, of Stockton, with her murder.

This week, the Alameda County Sheriff’s Office received information from the San Joaquin Sheriff’s Office about Dacany, an inmate there. He acknowledged responsibility for the homicide and provided details only law enforcement would know about the case, according to court documents.

A motive was not released.

Decany allegedly used a knife to kill St. John, according to court documents. He is also alleged to have killed her during the course of a robbery and burglary. Dacany was also charged with special circumstances of torture, which could make him eligible for the death penalty if District Attorney Nancy O’Malley seeks to pursue it.

He is also charged with arson.

St. John was found dead in the garage during firefighting efforts, but the fire was believed to have started in the attic of her home.

St. John raised her daughters in that house, but lived alone there since her husband’s death in April 2016. She was an optician at Foothill Optometric Group in Pleasanton.

After her death, the sheriff’s office released an image from surveillance video which showed that the person of interest may have been driving 2011 to 2013 silver Toyota Corolla.

Dacany is currently in custody in another California county and is awaiting transfer to Alameda County, according to the DA’s Office.