A New Jersey man has been arrested in connection to the grisly ax-murder of his sister-in-law and niece, who were found dead underneath a mattress last month inside their Roselle home.

Everoy L. Morrison, 44, was charged with two counts of first-degree murder, motor vehicle theft and several weapons counts in connection to the late April killings, the Union County prosecutor’s office said Monday.

The bloodied bodies of Kiesha Morrison, 45, and her 9-year-old daughter, Kelsey, were discovered underneath a mattress in the daughter’s bedroom by police who were called to a home at West 7th Avenue on April 18 after the two were reported missing.

Initial reports said the mother and daughter, who was days short of turning 10, were bludgeoned to death, but later reports claimed an ax had been used.

After the victims’ bodies were discovered, police determined that Keisha Morrison’s brand-new BMW had been stolen.

Investigators from the Prosecutor’s Office Homicide Task Force and the Roselle Police Department were able to track the vehicle to Maryland.

There, the driver, Everoy Morrison, was pulled over and arrested for being in possession of the stolen car.

Following an investigation involving the Roselle police, the prosecutor’s office task force with assistance from the Union County Sheriff’s Office Crime Scene Unit and the Maryland State Police, officials were able to identify Everoy Morrison as the suspect in the case.

The brutal slayings reportedly followed a domestic dispute in the home, which is owned by Keisha Morrison’s husband, Gary Morrison.

Everoy Morrison had been living in the basement of his brother’s home for two years but had recently been told that he needed to move out.

Atasha Scott, the sister of Keisha Morrison’s husband, told NBC New York that police said the killer “wrapped them up in bed sheets, stuffed them under my niece’s bed.”

Gary Morrison found the murder weapon, a bloody ax, stuffed between two mattresses in his bedroom.

“On the floor, it seemed like somebody was trying to clean up blood like it was swirled around,” Scott told the outlet.

The family suspected that Everoy Morrison was envious of his brother’s life.

“The guy was jealous of my brother and what he had. He wanted what he had,” said Scott.

Everoy Morrison is currently being held in the Baltimore County Detention Center awaiting extradition proceedings.

Authorities have not shared a potential motive for the brutal slayings.

“We are appreciative of the collaboration with the local and Maryland law enforcement agencies who assisted our office in locating and apprehending the suspect,” Union County Prosecutor William A. Daniel said in a statement.

“And we hope that this arrest can bring some small measure of comfort to all those grieving Keisha and Kelsey.”