Killer grandmother reveals in chilling seven-page letter to cops why she gunned down her son’s ex-girlfriend as she loaded her one-year-old baby into a car in posh NYC neighborhood

A terminally ill grandmother who shot her son’s ex-wife to death in a gruesome murder-suicide detailed allegations of abuse in a seven-page letter.

Kathleen Leigh, 65, claimed her former daughter-in-law Marissa Galloway, 45, attempted to alienate her four-year-old daughter from her son – the girl’s father – in the note found in her pocket. told the New York Post.

She also wrote that no one believed her and her sons’ claims that Galloway had abused the girl. New York City Child Protective Services investigators twice determined that the allegation was unfounded.

The letter — with the words “For the police” written on it — was found on Leigh’s body after she shot Galloway in the head and back while putting her 1-year-old child in a car seat in the backseat of a parked car on the Upper East Side Friday morning.

According to police, Leigh then committed suicide by shooting himself in the head.

Leigh shot and killed mother of two Marissa Galloway (pictured) on a Manhattan street Friday morning before killing herself

The 4-year-old girl, who was not with her mother or grandmother at the time of the shooting, had been the subject of a years-long custody battle between Galloway, a special education teacher, and Leigh’s son.

According to the Post, both sides accused each other of child abuse during the fight.

In some reports, the girl’s father claimed his daughter would come home with bruises on her arm, but investigators found these allegations to be unfounded.

Leigh has even filed the claims with her neighbors in a Manhattan apartment building where she has lived with her son for the past three years.

Galloway was putting her one-year-old daughter in a car seat in the backseat of a parked car when she was shot

She always talked about being a former [partner] “That was really annoying, because one evening child protective services came to my door asking if I had ever heard of any problems with the neighbors,” said neighbor Meryl Feidelman.

“I said, No, no, she’s a sweet, sweet mother, a sweet woman.”

According to NYPD Chief of Detectives Joseph Kenny, Galloway also had a history of domestic violence with her partner, related to the custody battle.

Between July 2021 and November 2021, five reports and two complaints were filed with the NYPD, but no arrests were made.

Galloway has been battling Kathleen’s son, the child’s father, for custody of her four-year-old since 2021. The one-year-old is not Leigh’s son

The child is now in the custody of Leigh’s son as the NYPD continues to investigate the murder, which occurred just a stone’s throw from Mayor Eric Adams’ home.

She was with her father when her grandmother murdered her mother on the normally quiet, tree-lined street just before 9 a.m.

Two weapons were found at the crime scene: a 9mm weapon on the sidewalk and another weapon in the Target bag Leigh was carrying.

Police are trying to determine whether Leigh had the guns in her possession while working as a probation officer in Chicago, where she worked for 17 years before retiring in 2014.

However, according to the Post, officers believe she acted alone in the killing and have no evidence her son knew of her plans.

Still, Galloway’s family could be entitled to at least some custody of the 4-year-old under special circumstances that arise “when the mother is murdered in cold blood,” a custody attorney told the Post.

Her other child, a one-year-old girl whose father was reportedly a sperm donor, is now with her maternal grandparents in New Jersey.