MAYS LANDING, N.J. — A 28-year-old man has acknowledged in court that he fatally beat his pregnant partner with a baseball bat, concluding a murder case initially characterized by a misleading claim of an accidental fall.
Boris Lainez-Rosales formally entered a guilty plea to first-degree murder on May 19, relating to the death of 25-year-old Leslianette Quintana-Betancourt. In accordance with the plea agreement, he faces a proposed sentence of 30 years in New Jersey State Prison without the possibility of parole. The court will officially sentence him on July 31 under the oversight of Superior Court Judge Joseph A. Levin.
According to the Atlantic County Prosecutor’s Office, Lainez-Rosales admitted to the assault on his partner at their Pleasantville residence on December 2, 2024. At the time, Quintana-Betancourt was not only his partner but also pregnant. The state is represented by Executive Assistant Prosecutor Rick McKelvey, while the investigation was conducted by the Pleasantville Police Department along with the prosecutor’s Major Crimes Unit.
Lainez-Rosales’ first account to the authorities did not include a confession. He called 911 shortly after 2 a.m. on December 3, stating that Quintana-Betancourt had fallen down the stairs and was unresponsive. Upon arrival, first responders found her at the bottom of the staircase, and the initial assessment suggested an accidental fall. However, discrepancies soon emerged that contradicted this narrative.
An affidavit detailing witness accounts indicated that prior to the emergency call, there had been a prolonged argument between the couple, lasting from approximately 9:30 p.m. to 11 p.m. on December 2. A witness present in the home had gone downstairs to investigate the noise and was sent back upstairs by Lainez-Rosales, who claimed everything was fine. This timeline proved crucial, as it placed both individuals together during a tense period leading up to the emergency call.
As the investigation unfolded, evidence began to tell a different story. Quintana-Betancourt suffered significant blunt-force trauma to multiple areas of her body and experienced a ruptured placenta, which resulted in the loss of her unborn child. Inconsistent details, such as a lack of blood stains in the stairwell where she was found, raised red flags. A bleach odor at the scene further complicated the situation, suggesting efforts were made to clean up after the incident.
Authorities also discovered bloodstains throughout the basement of the apartment and signs of attempted cleanup. Notably, a baseball bat covered in blood was recovered from the yard, alongside a trash bag from Lainez-Rosales’ vehicle containing possible remains of hair. These findings led investigators to suspect that the fall narrative was fabricated after the assault.
Lainez-Rosales was indicted in February 2025, facing charges of murder, tampering with evidence, and unlawful possession of a weapon. His guilty plea to first-degree murder alleviates the need for trial proceedings, acknowledging that the fatal blow was delivered with a bat in their Pleasantville home. While the plea proposes a specific sentence, the final decision rests with the court at the upcoming hearing.
Friends and family of Quintana-Betancourt have commemorated her as a loving sister, daughter, and friend, eager to embrace motherhood. An online tribute expressed her excitement about the new chapter in her life, highlighting her kindness and the ability to light up a room with her laughter. Such remembrances contrast sharply with the grim circumstances of her untimely death, underscoring the tragedy at the heart of this case.
With the sentencing date approaching, Lainez-Rosales prepares to face the consequences of his actions, while the community grapples with the loss of a promising life. Prosecutors are expected to advocate for the full 30-year sentence, as established in the plea agreement.