A man and woman arrested on suspicion of trying to kill Yakima real-estate broker Vernon Holbrook while posing as prospective homebuyers were ordered held Tuesday on $750,000 bail while investigators seek a motive.

Luis Gomez-Monges, 38, and Adriana Mendez, 23, were arrested Monday by Yakima County sheriff’s detectives, two days after Holbrook, 78, was found in a pool of blood at a home in the Cowiche area Northwest of Yakima.

He had been severely beaten and his throat was cut.

According to arrest affidavits, Mendez told detectives she and Gomez lured Holbrook to a vacant home by posing as prospective buyers and had asked for him specifically after calling his agency, Aspen Real Estate.

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The affidavit cites no motive for the attack, however, and Chief of Detectives Stew Graham said Tuesday he was unaware of one.

Holbrook was found by a colleague Saturday evening after he left to show homes in the Tieton-Cowiche area and never returned.

The colleague found Holbrook unconscious after a neighbor retrieved a key and entered the house. Authorities said the attack was so vicious that Holbrook suffered multiple fractures to his skull and to an eye socket. His throat had been cut; the weapon narrowly missed an artery, deputies said.

A search warrant of Holbrook’s phone records revealed he had received a call from a phone belonging to Mendez shortly before he stopped answering his phone late Saturday morning.

After initially denying involvement, Mendez told deputies that she and Gomez lured Holbrook to a vacant home by posing as prospective homebuyers from Texas, according to arrest affidavits.

Holbrook was last listed in critical condition at Harborview Medical Center in Seattle.

Wednesday night, however, the hospital had no record of him being a patient there.