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Uber is losing yet another top engineer from its self-driving arm in the aftermath of its acquisition of self-driving trucking startup Otto.

Raffi Krikorian, the senior director of engineering at Uber’s Advanced Technologies Center in Pittsburgh, is stepping down from his role at the company, sources told Recode. Krikorian, who was previously the vice president of engineering at Twitter, joined Uber’s Advanced Technology Group in March 2015 to lead the more than 50 roboticists and engineers that the ride-hail company recruited from Carnegie Mellon University.

In an email to employees on Monday, Krikorian said he wanted to take time to focus on his family as they move to California. But, Krikorian wrote, he may return, though not in his original role.

"When I’m ready to jump back in, I’ll figure out where I may be able to best help the ATG at that time," he wrote.

Update: Krikorian tweeted that he is officially leaving the company.

In the meantime, the company is looking for a new permanent software lead to replace him.

"In the interim," Krikorian wrote, "[David] Stager will continue in his role as Autonomy lead, Don Burnette will continue as the Autonomy tech lead and Paw Andersen (a new senior director joining from HQ who has been leading the Business Infrastructure and Marketplace/Dispatch teams for the last couple of years) will be taking point on the rest of the software team including AVMaps — the three of them will report to [Anthony Levandowski]."

Krikorian is just one in a series of top engineers who have left the ATG since Uber acquired Otto in August 2016. As part of the acquisition, Uber CEO Travis Kalanick put Otto co-founder — and one of the first employees of Google’s self-driving car project — Anthony Levandowski at the head of all of its autonomous technology efforts.

As part of that move, Krikorian began reporting to Levandowski.

i'm excited to say that i've joined @uber's advanced technologies center! pic.twitter.com/MXapZIT8ue — uɐᴉɹoʞᴉɹʞ ᴉɟɟɐɹ (@raffi) March 25, 2015

Before Krikorian’s departure, Brett Browning, Drew Bagnell and Peter Rander — all of whom were poached from Carnegie Mellon — left the company, as Recode first reported. Rander went on to launch a self-driving startup called Argo.ai alongside Google self-driving engineer Brian Salesky, which Ford rather quickly acquired a majority stake in.

Browning, who headed up mapping at Uber, has joined Salesky and Rander as Argo.ai’s vice president of robotics, and the company has also hired Tyler Krampe, who was at the ATG as a senior software lead for more than a year and a half.

This comes at a time when Uber is doubling down on its autonomous efforts. Earlier this week, the company launched its commercial self-driving pilot of semi-autonomous cars in Arizona.

The pugnacious ride-hail company shipped its cars to Arizona after coming up against the California DMV in San Francisco for not getting regulatory approval to operate semi-autonomous cars on public roads. It’s not clear why the company chose to roll out the pilot in San Francisco in the first place, though sources say Uber higher-ups were looking for a splashy launch close to investors.

Originally, as sources told Recode and we reported earlier, the ATG’s plan was to begin testing its self-driving cars in Arizona before California, and it had already begun mapping parts of the state.

This changed around the same time Otto was acquired, according to sources.

Uber declined to comment for the story.

If you have any additional information you can contact this reporter at johana@recode.net or on Signal, Confide or Telegram at 5162338877.

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