Deputy Romero said on Monday that the authorities did not know the finer details of how the call was placed, adding, “All we know is Alexa saved a life.”

Pressed about the doubts raised by Amazon, she said on Tuesday in an email that Alexa was used “along with the home phone system” to call 911.

Referring to Ms. Honorio, Deputy Romero wrote: “The 911 recording is consistent with her statements, as she can be heard screaming in the background, ‘Alexa call 911.’ I cannot confirm which device was connected to the home phone system.”

Glenn Platt, director of interactive media studies at the Miami University, in an email on Tuesday outlined a series of steps that might explain what happened.

The Echo can’t interpret what you mean, but it can activate calls that are in a contact list, he wrote.

“So if you have ‘mom’ on your phone in your contact list, you can say ‘call mom’ and then your phone will call mom,” he wrote. “But if, for example, you say, ‘call the police’ and there is not a contact on your phone called ‘the police’ then the Echo (Alexa) won’t be able to call it.”

He said Echo has “skills,” which are permissions and rules tied to a user’s personal account and information. Even if the device heard “call the sheriff,” it would not have done anything. It would have had to be prompted first by one of the key words, have the phone skill enabled and a number in the contact list for “the sheriff.”