Authorities have charged a former partner of a mother of four with her murder, following her fatal stabbing in the hallway of her Harlem apartment complex, according to police reports on Tuesday.

Police sources revealed that Luis Marquez, under the influence of alcohol, felt slighted because he considered Lopez the love of his life, while she did not reciprocate those feelings.

The tumultuous relationship between Marquez and Lopez was characterized by frequent breakups and reconciliations, sources indicated.

Marquez allegedly lurked in the building’s stairwell for over two hours before ambushing Carmen Yadira Lopez. He is accused of stabbing her nearly 50 times after she exited the elevator onto her floor at approximately 4:25 a.m. on Monday. Neighbors recounted to the Daily News that Lopez’s desperate pleas for Marquez to desist could be heard.

The 31-year-old Marquez now faces murder charges for the attack inside the apartment complex located on W. 129th St., near St. Nicholas Terrace. Authorities apprehended him later that same day.

Building porter Lyron Middleton, who discovered Lopez’s body upon starting his shift on Monday, recounted the harrowing scene, having reviewed surveillance footage of the brutal incident. “You could hear her screaming, ‘Stop, Luis!’ ‘Luis, stop!’” he recalled.

“She was on the floor and I saw the blood,” he said. “Her face and her hand was all bloody. She still had her keys in her hands. Her eyes were wide open. She was faceup … I called 911. I never seen anything like it.”

Zameon Price, 35, a public school dean who lives in the building, also heard Lopez’s heartbreaking pleas for help.

“She was screaming … ‘Leave me alone! Get away from me! Help! Stop!’” he said. “I thought it was regular people fighting. … Thinking about it now, I feel bad (that) I could’ve possibly helped, I could’ve possibly stopped him.”

Marquez was caught on surveillance cameras waiting in a stairwell by the building’s third floor before he jumped Lopez as she stepped off the elevator, police sources said.

Medics rushed her to Mount Sinai Morningside hospital but she could not be saved after suffering nearly 50 stab wounds.

“She was a great mother and a great human being,” Lucy Lopez, the victim’s sister, said. “She loved our family and she loved life. We don’t know how to start over.”

Marquez was hospitalized overnight before being returned to the 26th Precinct stationhouse for questioning Tuesday. His arraignment in Manhattan Criminal Court was pending on Tuesday

Marquez, who lives in the Highbridge section of the Bronx, had no prior arrests, sources said.

Carmen was a mother of four, with two of her kids, ages 7 and 14, still living at home, and two adult sons who live elsewhere. She shared the apartment with her mother, with the family having lived in the building for decades.

“She was a very nice person,” the building’s distraught super said.

“I knew her for a long time. Her mother used to watch my son when my son was little.”

The killing was the first time police were alerted to the apparently tumultuous relationship between Lopez and Marquez, police sources said. Lopez had never filed an assault or harassment claim against Marquez.

The building super, who wished not to be named, watched surveillance video showing the slaying but declined to describe to reporters what he had seen.

“I saw her on the cameras when the problem happened,” he said. “I don’t want to talk about that.”