The video footage is grainy, but the violence is clearly visible: When sheriff’s deputies catch the suspect fleeing down a San Francisco street, they tackle him, then begin hitting him. First, they use fists, then batons, swinging the clubs down with both hands as the man lies on the ground, moaning.
As the video of the arrest began to circulate on Monday, the suspect, Stanislav Petrov, remained in the hospital, and a criminal investigation had begun of the two Alameda County sheriff’s deputies who were shown delivering the blows.
Brendon Woods, the Alameda County public defender, compared the video to the one that showed the beating of Rodney King by Los Angeles police officers in 1991 — one of the first cases in which video of officers’ use of force stoked public outrage.
“The visuals are very similar: You have someone on the ground, who for all intents and purposes has given up, being hit over and over again with a baton,” Mr. Woods said. “He’s not resisting. The visuals are just shocking.”
Mr. Woods met with Mr. Petrov, whom he expects to represent, on Sunday night in the hospital, and said he had numerous injuries, casts on both arms, and hands that appeared to be “shattered.”
Sgt. J. D. Nelson, a spokesman for the Alameda County sheriff, said that an internal investigation was underway, and that the deputies were placed on administrative leave on Sunday. “The sheriff was clearly concerned about it,” he said of the video.
The pursuit of Mr. Petrov began early Thursday morning, when he was found with a stolen car, Sergeant Nelson said. Mr. Petrov crashed the vehicle into two patrol cars and knocked down a deputy, Sergeant Nelson said. He then led deputies on a 40-minute chase from San Leandro through Oakland into San Francisco, where he hit a parked car and tried to flee on foot. That was where the video picked up, just before deputies tackled him about 1:30 a.m.
Mr. Petrov had several warrants for his arrest, including one for assault with a deadly weapon, Sergeant Nelson said.
Footage of the arrest was taken by a motion-triggered security camera on a nearby building and released by the San Francisco public defender’s office. Although the deputies appeared to hit Mr. Petrov for about 20 seconds, the blows probably went on for about twice that long, said Tamara Barak Aparton, a spokeswoman for the public defender’s office, because the camera recorded in intervals of 10 seconds on and 10 seconds off.
The deputies, whose names were not released out of concern for their safety, can be seen delivering more than 30 blows to Mr. Petrov.
The San Francisco Police Department and the district attorney’s office have begun a criminal investigation. Mr. Woods also called for a federal civil rights inquiry and an external review of the sheriff’s office’s use-of-force policies.
Mr. Woods said the video pointed to the importance of body cameras for police officers. “If you’re fleeing or have done something to antagonize officers,” he said, “they often feel use of force is justified, which is not the case.”
