Relatives of passengers on Malaysia Airlines flight MH370, which inexplicably vanished nine years ago, urged the Malaysian government to permit Ocean Infinity, a U.S. seabed exploration company, to conduct a new search for the missing aircraft.

When aircraft MH370 vanished on March 8, 2014, while traveling from Kuala Lumpur to Beijing, it cemented its place as one of the greatest aviation mysteries in history.

In 2018, Malaysia engaged Ocean Infinity to search for the aircraft in the southern Indian Ocean, offering to pay up to $70 million if it found the plane. But its operation came up short.

The firm’s search came after Malaysia, China and Australia ended a fruitless two-year, A$200 million ($135.36 million) underwater hunt in January 2017 after finding no trace of the plane.

On Sunday, Voice370 – a grouping of relatives of those aboard the plane – said Ocean Infinity hoped to embark on a new search as early as this summer and urged the Malaysian government to accept any proposals from the firm on a conditional fee basis, such that the firm would only be paid if successful.

“Ocean Infinity, over the last 12 months have made real progress working with many people to further understand… the events in 2014,” Voice370 said in a statement, following a memorial event to mark the ninth year since MH370’s disappearance.

“Ultimately, this has greatly improved their chances of conducting a successful search.”

Ocean Infinity and Malaysia’s transport ministry did not immediately respond to a request for comment.

But in a message to families read out at the memorial event, Transport Minister Anthony Loke vowed not to “close the book” on MH370, adding that due consideration would be given to future searches if there was “new and credible information” on the aircraft’s potential location.

Debris confirmed or believed to be from the MH370 aircraft has washed up along the African coast and on islands in the Indian Ocean.

Malaysian investigators previously drew no conclusion about what happened aboard the flight, but did not rule out the possibility that the aircraft had been deliberately taken off course.