Dunwoody, Georgia, police Detective Jesus Maldonado took the stand Monday morning and told a judge why a 15-year-old girl was stabbed 53 times by her brother: She took too long in the bathroom, he said.

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Moldonado testified that Gavin Henderson, 27, had moved into the Lacota Apartments in metro Atlanta with his mother, Rochelle, and his siblings after he was released from a Florida prison last year. He had served several years for violent crimes, records show, and had nowhere else to go.

But the family found Henderson to be ornery. Once, Maldonado testified, he pulled a knife on another of his sisters. But no one called the police. The family diffused the situation privately.

Then on June 18, around 3 p.m., Henderson needed to use the bathroom, but his sister, Keaira Henderson, a 15-year-old Alpharetta High School student, was already using it.

Their mother was at work in Alpharetta. A 12-year-old was at the apartment on Peachtree Industrial Boulevard with her siblings and would later speak to police.

"She said there was an altercation about Keaira taking too long in the bathroom, which led to the fighting," Maldonado testified.

Henderson allegedly got a 10-inch hunting-style knife and followed Keaira as she ran outside and started banging on neighbors’ doors for help. No one could save her.

The 12-year-old stayed in the apartment, terrified. She called her mom, who began racing home from work and dialed 911 on the way to say something — she wasn’t sure exactly what — was happening.

In the moment Henderson stabbed his sister the first time, a thought occurred to him, according to his alleged statements to police: This will send me back to prison.

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So, as Maldonaldo told it, Henderson felt there was “no turning back” and decided to keep stabbing.

The 12-year-old opened the door and saw the killing.

Neighbors repeatedly heard Keaira scream: “No! Please stop!”

Henderson, bloodied by the violence, walked to a nearby store, the detective said.

He allegedly placed the knife on the counter and asked the clerk to call 911. He told her there had been an “accident,” gesturing to the wet crimson on his hands and T-shirt.

Police arrived and arrested him, soon filing murder charges. When officers looked over Keaira’s body, they couldn’t count how many times she’d been stabbed, except that it was far too many to survive. The medical examiner’s office came up with 53.

In the days after, friends and family lamented the girl, who had wanted to be a lawyer and was liked enough at her school that friends gathered on the football field to remember her.

There was no family in the courtroom to hear all this, though they would likely know much of it already because it played out in front of the 12-year-old.

Henderson, whose attorney made no argument on his behalf, sat stoically in court.

When the judge said there was enough evidence for the state to continue its prosecution, Henderson rose and went with deputies back to his cell, the place he'd known he was going from the first thrust of the knife.