Less Schnabel Jr. was sentenced to up to 20 years in prison today for killing visitor Christopher Reuther in a one-punch, unprovoked assault on a Nanakuli beach last year.

Reuther's mother, Judy Wilson, told Circuit Judge Michael Town that she has been diagnosed with "invasive breast cancer" that various doctors said was caused by the stress of her only son's death.

She asked Town for the maximum sentence, while Schnabel's mother, Theona, asked the judge to have mercy on her son.

Schnabel, 23, apologized to the Reuther family and blamed the assault on his addiction to crystal methamphetamine. He said he has been clean of the drug and been gainfully employed since being released on bail in the manslaughter case.

Town imposed the maximum sentence "without a lot of hesitation."

"Someone's life is gone," Town said. The attack on Reuther, 34, "was unprovoked, it was tragic and I can't understand it," said Town.

Reuther was punched in the head after he took Schnabel's photograph in the parking lot of Zablan Beach Park in Nanakuli near midnight April 22, 2007. He died at Hawaii Medical Center-East on April 24.

Reuther came to the Islands to visit the William S. Richardson School of Law at the University of Hawai'i. An honors graduate from the University of North Carolina who had been working as a magazine photojournalist, Reuther had been offered a partial scholarship to enroll in the environmental law program here.

Prosecution witnesses in the manslaughter trial testified that Schnabel punched Reuther once in the side of the head and said the attack was unprovoked.

Reuther fell senseless to the ground and died two days later of a lacerated artery at the base of his brain.

Various witnesses said Schnabel was angered after Reuther unexpectedly took a photograph of him in the parking lot and twice told Reuther to "get the f--- out of here."

Reuther was an organ donor, and at least five people received organs or tissue from him.