(NewsNation) — Navy officer Lt. Ridge Alkonis, jailed in Japan over a deadly car crash, is now in United States custody.

Alkonis is now being returned to the U.S after what his family said has been 507 days of detainment. He had been serving a three-year prison sentence after pleading guilty to the negligent driving deaths of an elderly woman and her son-in-law in May 2021.

The 34-year-old said he was struck with a case of altitude sickness and lost consciousness while driving with his wife and children near Mount Fuji, causing him to slump over behind the wheel. This was supported by a neurologist’s diagnosis. However, a panel of three Japanese judges maintained that Alkonis fell asleep and should have pulled over.

Although Alkonis agreed to pay the victims’ families $1.6 million, the panel still decided to sentence him.

In a statement to NewsNation, Alkonis’ family said they appreciate the United States government’s work on the transfer, and are glad an “impartial set of judiciary eyes” will review his case for the first time.

“When the Biden administration is presented with the complete set of facts and circumstances surrounding the case, we’re confident they will promptly recognize the absurdity of Ridge’s conviction,” Alkonis’ family said.

However, the family said they cannot truly celebrate until Alkonis is back with his family.

It was unclear where in the U.S. Alkonis is heading or whether upon his arrival in the country he might be required to spend any additional time behind bars under the terms of his transfer from Japan.

Ridge Alkonis’ wife, Brittany, had been a staunch advocate for his release. Brittany Alkonis had met with the National Security Council group tasked with trying to negotiate his transfer, and she and others also spoke directly with President Joe Biden, Vice President Kamala Harris and the National Security Adviser.

Members of Congress also expressed support for Alkonis and his family, and attempted to elevate his case.

This story is developing. Refresh for updates.

Previous reporting from NewsNation correspondent Joe Khalil and The Associated Press contributed to this report.