Mahr Vehl is a Kar Ree, who defected from the ranks as he hated the antagonistic behavious of the society.
Kar Ree Armada
Mahr Vehl spent his early adulthood as part of the Kar Ree's Armada, a ground-based task force dedicated to protecting the surface of the planet. He was part of the Armada for three years, and saved countless people from near-certain death. It was during this time that he first came into contact with the mighty Garr Laac Tus, after he had been blasted off the planet. The "Eater of Worlds" offered him a deal, if Mahr Vehl helped the entity destroy all resistance on a planet, he would give the Kar Ree all the riches he could want. To complete the being's task, he tricked the Kar Ree Armada into kill off all life, and as such resistance, on the planet Xandar. Garr Laac Tus turned over all the planets wealth to Mahr Vehl, but he realised he'd done something so bad he could never forgive himself. He handed the riches over to the Kar Ree Government, and defected from the ranks.
After flying through the galaxy for several months, Mahr Vehl came across the planet Earth. After monitoring the people for a few days, he decided he wanted to live on the relatively peaceful planet. He went and found a surgeon, to make his appearance humanoid, and after several days of surgery, he travelled to Earth with a holographic projector, and set himself up as a doctor in Manhattan under the name "Philip Lawson".