Six months after a University of Michigan doctoral student mysteriously vanished while piloting a plane — which eventually crash-landed in Canada — a woman who says she is his wife is asking a judge to declare him dead.

Xin Rong, who was 27 at the time of his disappearance, has been missing March 15.

The downed Cessna he had been flying was found in a densely wooded area in Ontario the same day he rented the aircraft from a flying group at the Ann Arbor Airport. But Rong was not there, there were no footprints in the snow and the plane was out of fuel, authorities have said.

A spokesman with the Ontario Provincial Police previously said authorities believe Rong jumped from the plane at some point during the flight. At the time, police said suicide was suspected.

Read more:

Mystery surrounds U-M student's final flight

2 hurt in Lenawee County plane crash undetected for 4 hours

In a petition to have Rong's death established by a Washtenaw County probate judge, Surong Ruan, who says in court filings that she is his wife, wrote: "All the evidence indicates the aircraft was operating normally and crashed because it ran out of fuel, and at some point prior to the crash, the pilot exited the aircraft. As ground searches were negative, no parachute or life vests on the plane and the aircraft was cruising at around 9000 ft altitude, I believe Xin Rong exited the aircraft and didn't have a chance of being alive."

A hearing on the petition is scheduled for next month.

An official with the court said such petitions ask for the court to establish the cause, date and location of death.

His wife sought an earlier hearing in the case — rather than waiting months to publish notices of the hearing in a newspaper — but online court records indicate her request was denied.

In a letter to Judge Julia Owdziej dated May 31, she wrote that she lives in San Francisco and Rong's parents live in China and said she is trying to take care of his property and address questions from insurance companies and the club that owned the plane Rong had been flying.

"I cannot address some of these matters until there is a declaration that he is deceased," she wrote.

Reached by phone on Friday, she said she was not available to talk and hung up.

Last week, Diane Brown, a spokeswoman for the U-M Division of Public Safety and Security, said the investigation remains open and wrote in an e-mail that police "don't have any new information to release."

Rong was pursuing a PhD in the university's School of Information and had an interest in aviation. A member of the flying club, who could not be reached last week, previously told the Free Press that Rong was a certified pilot.

On March 15, he flew out of Ann Arbor in a 1984 Cessna 172P owned by the Michigan Flyers. When it was overdue to return, authorities were notified and the wreckage was found in a forested area near Manitouwadge, Ontario, northeast of Munising over Lake Superior.

Documents filed in the probate case offer more details about his disappearance. In her letter to the judge, his wife wrote that Rong's wallet, iPad and other personal items were found in the plane.

Also included in the court file is a letter from a university police sergeant dated March 24 that says, in addition to searches around the plane crash site, a search was conducted in the Petoskey area, "where Mr. Rong's cellphone last pinged. Results were negative."

A spokesman with the Ontario Provincial Police last week would not confirm whether the cell phone pinged to any towers in Canada and said their investigation would remain open until Rong's whereabouts are known.

Contact Gina Kaufman: 313-223-4526 or gkaufman@freepress.com.