WASHINGTON — The teenager who filmed African American George Floyd’s murder by a white police officer one year ago marked the anniversary of his death on Tuesday, saying the video helped bring justice but had left her traumatized.

Darnella Frazier, then 17, took out her phone in Minneapolis and recorded Derek Chauvin kneeling on Floyd’s neck for more than nine minutes, providing crucial evidence that led to Chauvin’s conviction.

“A year ago, today I witnessed a murder,” Frazier wrote in a Facebook post. “I knew that he was in pain. I knew that he was another black man in danger with no power.”

“It changed how I viewed life. It made me realize how dangerous it is to be Black in America,” she wrote.

“I still hold the weight and trauma of what I witnessed,” she said, explaining how she used to shake at night so much that her mother had to rock her to sleep, and that she had panic attacks when seeing a police car.

“If it weren’t for my video, the world wouldn’t have known the truth,” she added. “My video didn’t save George Floyd, but it put his murderer away and off the streets.”

Frazier, who testified at Chauvin’s trial in April, was walking her nine-year-old cousin to the shops when she witnessed Floyd’s death — an incident that sparked protests across the United States over racial injustice and police misconduct.

On Tuesday, Floyd’s family appealed for sweeping police reform as they met President Joe Biden at the White House for commemorations marking his death.