PORTLAND – A university professor from Maine conquered Mount Everest, reaching the summit on his 36th birthday.

John Bagnulo of New Vineyard made it to the 29,035-foot peak, but his climbing partner, Bill Yeo, 40, of Durham, did not.

“We know they’re safe and they’re well and that John made it to the top yesterday on his birthday,” Yeo’s wife, Julie, said Thursday.

It was not immediately clear why Yeo did not complete the climb.

“We heard from climbers on the mountain that both guys were very strong and both were doing good,” said George Martin, manager of the Web site everestnews.com, which tracks ascents of the world’s highest mountain.

Yeo, an employee of L.L. Bean, and Bagnulo, a nutrition professor at the University of Maine at Farmington, were back at advanced base camp and out of danger, Martin said.