A guilty conscience and a neighbor’s good memory have helped Houston police solve the 1999 murder of a 93-year-old woman.

The body of Novell McKissack was found in her home in the 5300 block of Petty in September of that year. Evidence showed she was strangled, stabbed and beaten during a robbery.

The crime shocked neighbors who said McKissack was like everyone’s favorite grandma.

"She was a fine Christian lady," Ed Griffith told KHOU 11 News back in 1999.

Despite a description and composite sketch, the case quickly went cold.

Fast forward to 2014 when San Diego Delgado wrote a letter confessing to the crime from his prison cell in Tyler. Delgado is serving time for a kidnapping and rape that happened the year after McKissack was killed.

Novell McKissack's tiny home is still standing. (Google Maps)

Delgado, who lived down the street from McKissack, said he broke into her home to support his drug habit. When she woke up, he said he “stabbed her a bunch of times… and didn’t stop till she was not moving.”

“He wanted to get it off his chest,” Harris County chief prosecutor Martina Longoria said. “It’s weighed heavily on him. Having seen the crime scene, the heinous nature of the crime would certainly weigh on you even if you’re serving an adult sentence in prison.”

Delgado told investigators he took money, jewelry and a television from the home.

When an HPD homicide detective interviewed Delgado, he told him other things only the killer would know, according to court documents.

A neighbor identified Delgado from a photo lineup as the man seen in McKissack’s backyard the night of the murder. His photo also matches the composite sketch from 1999.

It took investigators a couple of years to match all of the evidence, including DNA and fingerprints. Charges were filed this week.

Delgado is expected to face a Harris County judge for the capital murder charge on Wednesday. He was 15 at the time of the crime, so he won’t face the death penalty.