When a police officer is caught flagrantly misbehaving on video, the most that superiors and union officials typically concede is that he's an exception to the rule, a "bad apple." That can be true. There are something like one million cops in the U.S. Many do their jobs ethically, and even the best run police agencies sometimes find themselves employing a cop whose behavior is anomalously awful.

But the modern era of videotaped police brutality, which began when a group of LAPD officers nearly killed Rodney King, has also revealed a darker variation: the occasions when multiple cops participate together in obviously extra-legal assaults, where many throw punches and kicks and still others are silent bystanders whose complicity typically grows when they accede to fabricated police reports.

The latest illustration of this pattern occurred last week in San Bernardino County, California, where an NBC news helicopter captured the end of an unusual chase: a suspect fled on horseback across the wilderness while cops gave chase. In an initial use of force, one deputy used a Taser to knock him from his mount. "He then appeared to be stunned with a Taser by a sheriff's deputy and fall to the ground with his arms outstretched," NBC reports. "Two deputies immediately descended on him and appeared to punch him in the head and knee him in the groin."

He was quickly if not immediately subdued. Nevertheless, "in the two minutes after the man was stunned with a Taser, it appeared deputies kicked him 17 times, punched him 37 times and struck him with batons four times. Thirteen blows appeared to be to the head." As many as 11 sheriff's deputies were ultimately complicit, with only the very last to arrive on the scene having a plausible excuse:

San Bernardino County Sheriff John McMahon told the news station, "I'm disturbed by what I see in the video. But I don't need to jump to conclusions at this point, until we do a complete and thorough investigation." He should be disturbed. What the video suggests is that a number of San Bernardino County sheriff's deputies with no apparent connection save that they happened to arrive first to a suspect decided spontaneously to participate in a brutal, needless assault.

Jim Terrell, the man's attorney, posed this question about the sheriff's deputies captured in the video: "Did they just start being thugs or have they been thugs for years?” A local ACLU spokesperson worries it's the latter. "Community organizations have asked for federal authorities to step into San Bernardino County for some time,” Adrienna Wong told the San Bernardino Sun. She noted alarming frequency in the use of Tasers, four people killed since 2008 after being Tased repeatedly, and administrators who won't even release their Taser policy. It's terrifying to reflect on how few of their past arrests have been captured on video.

10 deputies have been put on administrative leave while the San Bernardino County Sheriff's Department investigates the latest incident. The FBI is also involved.