Lakisha Jenkins, the mother of Keyshaun Mason, 14, who was stabbed to death by her boyfriend, cries while her sister, Jonisha Surles, tries to comfort her at Potomac High School in Oxon Hill. (Evelyn Hockstein/For The Washington Post)

All through the night, Lakisha Jenkins and her boyfriend had been in their Oxon Hill apartment, arguing.

As Monday morning broke and the fighting continued, police said, the woman’s 14-year-old son and his brother tried to get the boyfriend, Sean Crawford, who was armed with a kitchen knife, out of the master bedroom, where the couple at one point had been barricaded.

But as the brothers forced their way into the bedroom to come to their mother’s aid, the boyfriend went after them, according to Prince George’s County police.

The 14-year-old, Keyshaun Mason, was fatally stabbed in the chest and his 18-year-old brother knifed in the shoulder by a man who for decades has struggled with mental-health issues, according to court records and the man’s family.

Potomac High School freshman Keyshaun Mason died on Tuesday after being fatally stabbed during a domestic dispute between his mother and her live-in boyfriend. The boyfriend, identified as Sean Crawford, has been arrested and faces a charge of first-degree murder in Keyshaun’s death. (WUSA9)

The man, Sean Crawford, 48, also has been the object of numerous peace orders by women who claimed to have been stalked or assaulted by him, court files show. In many instances, he was ordered to attend counseling or receive psychological treatment, court documents show.

Crawford has been charged with first-degree murder as Mason’s family and classmates mourn the Potomac High School freshman known for his broad smile and love of football.

“He would do whatever he could possibly do if he cared about you,” Mason’s mother, 39, said Tuesday. “They did what they felt was needed to see if I was safe.”

Jenkins declined to discuss the details of the dispute that brought police to her apartment on Audrey Lane on Monday morning.

She said that she and Crawford had been in a relationship for a “short time” and that she wanted to help him.

“You never think that helping someone will end up in this way,” Jenkins said. “From my heart, I felt I could be of help.”

A day after Mason’s death, Jenkins and other family members gathered outside Mason’s high school to thank students who have shown an outpouring of support for the family.

Keyshaun Mason (Family Photo )

“He was a hero,” said Tyrece Jones, a friend of Mason’s and also a Potomac student. “I respect what he did, because he was protecting [his] mother.”

Crawford’s father, Howard Crawford, said his son has a history of mental illness and substance abuse dating to his son’s early 20s. But every time his family persuaded Sean Crawford to seek treatment, his father said, he would sign himself out of the hospital or stop taking his medications.

“As many times as [he] was able to sign himself out, [he] would,” Howard Crawford said. He “wanted to get away from it. [He] felt there was a stigma on it.”

After years of trying to get help for his son, Howard Crawford said, they drifted apart. His son would threaten violence or revenge when relatives attempted to get him medical help, Howard Crawford said.

“He never thought he had problems,” said his father, 80. “He thought we did it out of meanness.”

Howard Crawford, who said he hadn’t seen his son in 20 years, said Sean Crawford had difficulties holding down jobs and often was homeless. He said he had worried that his son’s personality issues might erupt into violence against others, but he didn’t know it would end up with the police accusing his son of slaying a 14-year-old.

Mason’s brother has been released from the hospital and is staying with his father, Jenkins said. Sean Crawford is jailed and faces a bond hearing on Wednesday.

Mason’s death has devastated his mother, she said. After speaking with reporters outside Mason’s high school Tuesday afternoon, Jenkins collapsed in the parking lot in tears and had to be helped up.

“I loved Keyshaun’s drive,” Jenkins said. “A lot of people loved him.”

Mason loved football, playing running back and safety for the Patuxent Rhinos, relatives said.

“He wanted to make it to the NFL,” said his aunt, Carvetta Mason, 33. “He didn’t even get a chance to shine.”

A candlelight vigil is planned for Friday evening outside the family’s apartment, and there has been an outpouring of support on social media from Mason’s friends and classmates, who called him “Sway.”

“It’s sad that a child has got to lose his life by protecting his mother, and now he’s not here,” Carvetta Mason said. “He’s going to be missed.”

Jennifer Jenkins contributed to this report.