“I finally concluded,” Mr. Borgese said, “that Amazon knew the device was being used and preferred to sell content to anyone who possessed the device, rather than assist in returning it to its rightful owner.”

Drew Herdener, an Amazon spokesman, said only that the company acted in accordance with the law and cooperated with law enforcement officials. “Beyond that, we aren’t going to speculate on hypotheticals,” he wrote in an e-mail message.

The complaints have left Amazon with a new public relations dilemma. In July, when Amazon remotely deleted titles from Kindles, citing copyright reasons, it was accused of heavy-handedness. If the company were to shut down a Kindle that had been erroneously reported as stolen, it might be accused of playing cop, judge and jury. Then again, it is also possible that Amazon is simply avoiding the financial burden of adjudicating claims.

Whatever the reasoning, Amazon’s policy is hardly unique.

Sirius XM Radio also says it needs to see a subpoena from a police officer before it will deactivate or hand over information about missing radios. Patrick Reilly, a company spokesman, said the goal was “to protect the original subscriber who has lost the radio, but also not to incriminate someone who legitimately comes in possession of a radio.”

Radios that have been reported stolen, he added, are reactivated only after someone provides a “proof of purchase,” like a receipt from eBay.

But former customers who have inquired about the fate of their stolen radios have been dismayed at how little company representatives are willing to help.

“I still don’t understand why they couldn’t just notify the police department and tell them who has my radio,” said Dolly Richards of Kennewick, Wash., whose Sirius radio was plucked from a Chevy Blazer one recent Sunday morning. “I mean, there’s a whole police report about this break-in. They can’t call and say, ‘So and so just registered that radio’ ”?