While James hesitated to follow through with the murder, Sherry took matters into her own hands and killed Krystal herself. Together, they buried her in the basement to hide the evidence.
In the Cold Case episode (Season 1, Episode 9), Detective Lilly Rush receives a chilling anonymous phone call that reopens a 14-year-old mystery. Here is the story of that case as detailed on Cold Case Wiki and IMDb : The Anonymous Confession Cold_Case_1x09
As the detectives piece together the past, a tragic narrative of manipulation emerges: While James hesitated to follow through with the
Lilly Rush eventually tracks down the caller, who is revealed to be the older James Hogan. Even after 14 years, he is still willing to take the fall to protect Sherry. However, the detectives uncover that Sherry had been forging Krystal’s checks for years after the murder. While James faces the consequences for his part in the cover-up, the truth about Sherry’s role finally comes to light. "Cold Case" Sherry Darlin' (TV Episode 2003) - IMDb Here is the story of that case as
Sherry wanted Krystal's money and pressured the devoted, yet weak-willed, James to help her get rid of the elderly woman.