A 28-year-old New Jersey man is heading to prison after admitting he beat his pregnant girlfriend to death with a baseball bat before trying to make it look like a tragic accident.
On Tuesday, Boris Lainez-Rosales pleaded guilty to first-degree murder in a Mays Landing courtroom. The charge stems from the brutal December 2024 death of 25-year-old Leslianette Quintana-Betancourt inside the Pleasantville home they shared. Under the terms of his plea agreement, he faces a recommended sentence of 30 years in state prison with no chance of parole.
“In pleading guilty, the defendant admitted that on December 2, 2024, he assaulted the victim, who was his domestic partner, and pregnant at the time, with a baseball bat at his home in Pleasantville, causing her death,” the Atlantic County Prosecutor’s Office said in a news release.
Court documents lay out a disturbing sequence of events on the night Quintana-Betancourt was killed. According to a probable cause affidavit, a witness who was in the house heard the couple arguing between 9:30 p.m. and 11 p.m. When the witness went downstairs to see what was happening, they were “escorted back upstairs by Lainez-Rosales, who said everything was fine,” the affidavit notes.
“A short time after that, Lainez-Rosales came up the stairs to the main living quarters and used the witness’s phone to call 911,” the document states.
First responders arrived to find Quintana-Betancourt dead at the bottom of a 12-step staircase. She had suffered massive blunt-force injuries to her face, arms, and abdomen. She also had a ruptured placenta, and her unborn child did not survive.
Lainez-Rosales, who had visible cuts on his hands, told police his girlfriend had fallen down the stairs. However, investigators immediately noticed the scene did not match his story.
“There were no blood stains in and around the stairwell,” the affidavit says. Instead, police noted that the victim’s body smelled strongly of bleach.
When searching the couple’s basement apartment, investigators uncovered bloodstains scattered across the walls and living area. The entire apartment smelled of bleach, and police found clear “evidence of attempts to clean up biological evidence.” Outside in the backyard, officers recovered a blood-stained baseball bat. They also found a trash bag inside Lainez-Rosales’ car “with possible hair attached.”
He was arrested shortly after the discovery and indicted for her murder in February 2025.
Friends and family have remembered Quintana-Betancourt as a joyful person whose life was cut abruptly short.
“You were so happy about becoming a mom,” a friend wrote on her online tribute wall. “You were such a sweet and kind young lady that had a laugh and smile that would brighten up a room.”
The case was investigated by the Pleasantville Police Department and the Atlantic County Prosecutor’s Office’s Major Crimes Unit. Executive Assistant Prosecutor Rick McKelvey is representing the state. Lainez-Rosales is scheduled to be sentenced by Judge Joseph A. Levin on July 31.
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