An Uber driver has pleaded not guilty to rape and other charges for allegedly sexually assaulting and kidnapping a young woman in Boston. The case is separate from at least two other incidences of alleged sexual assault involving Uber drivers, both of which occurred within hours of each other on Sunday.

The plea comes at a time when Uber faces scrutiny over how the app-based car service vets its drivers, handles customer information, and treats journalists who write critical pieces about the startup.

Alejandro Done, a 46-year-old Uber driver, pleaded not guilty to rape, assault to rape, kidnapping and assault and battery, the Boston Globe reported, citing a statement from Middlesex District Attorney Marian Ryan. The victim, who was not named, was allegedly picked up by Done around 7:30 p.m. Dec. 6 after a night out with friends and told the Uber driver to drop her off at her home in Cambridge, according to the paper.

Although the Uber app lets customers pay drivers, Done told the woman that she needed to pay with cash and drove her to an ATM, and then drove her to a remote area when she got back in the car, the DA’s office said. That’s when the Uber driver allegedly got into the back seat and hit the woman before strangling her, locking the doors and covering her mouth. Done then allegedly sexually assaulted the woman, who reported the incident to police, the Globe reported.

An Uber spokeswoman, Kaitlin Durkosh, said the company would comply with the police investigation and called the incident a “despicable crime.”

The alleged rape isn’t the only sexual assault allegation plaguing Uber’s reputation in Boston. Within about three hours on Sunday, three woman claimed they were sexually assaulted by people who they said were “employed by a rideshare service,” according to a blog entry on the Boston Police Department’s website. An Uber driver has been tied to two of those cases, the Globe reported, although it was unclear whether the three incidents were related or if the same driver is suspected in all three cases.

“The victims in two or more of the cases indicated that they had utilized the Uber app to secure transportation,” Officer James Kenneally, a Boston police spokesman, told the Globe. Meanwhile, Uber said there was “no evidence to suggest any Uber partner was involved,” Uber spokesman Taylor Bennett told the paper.

Uber said Wednesday that a rape perpetrated by one of its drivers in Delhi, India, earlier this month spurred the company to improve its vetting process. Those improvements may include lie detector tests for drivers and using “scientific analysis and technology,” Uber said in a post on its blog entitled “Our Commitment To Safety.”

The startup has also come under fire for accessing BuzzFeed reporter Katherine Tassi’s Uber account containing personal information. Uber’s general manager in New York, Josh Mohrer, accessed the information after the reporter sent him a message, and then did so again because the journalist was “30 minutes late” for a meeting with Uber.  

In November, Uber faced scrutiny again after BuzzFeed uncovered the company’s plans to hire “four top opposition researchers and four journalists” to dig up dirt on reporters who write unfavorable reports about Uber. That story was written by Ben Smith, BuzzFeed’s editor-in-chief, not Tassi.