Amazon says it has considered adding facial recognition technology to its Ring doorbell cameras.

The company is telling Congress that facial recognition is a “contemplated, but unreleased feature” of its home security cameras.

U.S. Sen. Ed Markey wrote to Amazon CEO Jeff Bezos in September raising privacy and civil liberty concerns about Ring’s video-sharing partnerships with hundreds of police departments around the country.

The Massachusetts Democrat also expressed alarm that Ring may be pursuing face-scanning technology that could flag certain people as suspicious.

Markey released Amazon’s latest response Tuesday.

Amazon’s initial response to Markey said Ring doesn’t currently offer facial recognition. But in a follow-up, Amazon said it frequently innovates based on customer demand and facial recognition is an increasingly common feature in cameras made by competitors such as Google.