Six former eBay executives and staff have been charged with cyber-stalking in a campaign against a couple who ran a newsletter critical of the company.
Prosecutors allege the harassment included sending the couple live cockroaches, a bloody Halloween mask and a funeral wreath, as well as threatening messages.
EBay said it did not tolerate such behaviour and apologised to the couple.
The firm fired the employees last September after its own probe.
That inquiry also uncovered "inappropriate" communication by former chief executive Devin Wenig, but it did not find evidence he had been aware of the specifics of the campaign, eBay said.
"However, as the company previously announced, there were a number of considerations leading to his departure," it added.
Mr Wenig was not charged. He told the Wall Street Journal on Monday that what the charges allege are "unconscionable".
But prosecutors named several senior employees, including 45-year-old James Baugh, a former senior director of safety and security, and 48-year-old David Harville, the firm's former director of resiliency. Both were arrested on Monday.
US Attorney Andrew Lelling told a news conference that the alleged harassment campaign included threatening Twitter messages and several visits to the couple's home, with the intent to break into the garage and install a tracking device.
Several of the group are also said to have ordered "anonymous and disturbing deliveries to the victims' home, including a preserved fetal pig, a bloody pig Halloween mask, a funeral wreath, a book on surviving the loss of a spouse and pornography - the last of these addressed to the newsletter's publisher, but sent to his neighbours' homes", Mr Lelling said.
He called the alleged stalking an attempt from "pretty high up the chain" to "weaponise the internet" to protect eBay's brand. "This case struck us as something unique," he said.
In a statement eBay said it "does not tolerate this kind of behaviour. EBay apologises to the affected individuals and is sorry that they were subjected to this".