Those who commit suicide by cop don’t usually have the chance to apologize. But a man killed by police in San Francisco on Jan. 4 after he threatened them with what turned out to be an air gun has done just that.

“Please, don’t blame yourself,” read a note to police found on the cellphone of Matthew Hoffman, the 32-year-old man who was killed Sunday, as the Associated Press reported. “I used you. I took advantage of you.”

Hoffman staged a standoff with police in the parking lot of a police station. When he brandished the gun, two officers shot him a total of three times.

“You did nothing wrong,” Hoffman’s note said, as SF Gate reported. “You ended the life of a man who was too much of a coward to do it himself … I provoked you. I threatened your life as well as the lives of those around me.”

Hoffman had approached police earlier in the day and asked what kind of ammunition they use.

“We don’t know his motive or why he challenged the officers or approached them in the first place,” said police spokesman Albie Esparza, as CBS reported. “It was very erratic behavior by the suspect, very unusual.”

Police have been on alert after two officers were killed in Brooklyn last month by a mentally ill man who said he was responding to recent deaths of unarmed African American men at the hands of police.

“This is a job where very sadly we lose officers,” San Francisco Police Chief Greg Suhr told the AP. “It’s on all our minds. But we’ve got a job to do, so we’re going to do it.”