GALVESTON, Texas -- A father of three fighting leukemia is now facing a different battle: one with the Galveston Police Department."They abused their authority, pretty much. Thinking they can do what they want with people," said Isaac Walton, a League City resident who is accusing four Galveston police officers of beating him for no apparent reason.On Aug. 15, Walton, his wife, and three kids were on Galveston Island to celebrate his middle daughter's birthday. That morning, Walton says he left their hotel and walked to get the family breakfast. He paused along the seawall, and took a brief stroll on to a jetty."Next thing I know, I felt somebody grab me, and I grab my right arm, and this time I realize it's a police officer," said Walton. "Immediately I say, 'Sir, I have a PICC line on this side, and I have leukemia,' and they didn't listen to anything I have to say."A PICC line is a catheter that's implanted on a cancer patient's upper arm, used to directly infuse chemotherapy drugs into the patient.Walton says the officer beat him, and one officer used a Taser on him, before putting him into a police vehicle."The only thing I can think about was trying to get out of that situation safely, without pretty much dying," Walton said."They beat him, they put handcuffs on him, throw him in the back of a car, they don't charge him with anything, they tell him he's not under arrest, then they drop him off at an emergency room, and they just leave them there," said Joe Mathew, one of the attorneys representing Walton.That morning, Walton left the hospital and walked back to the Galveston hotel where his family was staying. His family eventually found him slumped over, along the side of the hotel. They drove him immediately to MD Anderson Cancer Center.While there, his wife took pictures of Walton's lacerations and abrasions. The University of Texas Police Department also wrote an incident report.Eventually, Walton was charged with resisting arrest. His attorney says that did not take place until September. The Galveston Police says it issued a warrant within days.The charges are currently not available on the Galveston County District Clerk's website.Galveston police met with Eyewitness News to dispute the allegations of police assault, but would not comment on camera.Galveston PD says its officers were responding to several calls that morning, that a Hispanic male was walking along the jetty looking disoriented and behaving weirdly. Walton is mixed race.The police department says an internal investigation is ongoing, but Walton's attorneys doubt that.They say they have not been able to obtain any information relating to the charges or the arrest.Meanwhile Walton, who is still fighting leukemia, is now scheduled for a stem cell transplant in an effort to save his life.Walton's family also has a GoFundMe site to help with some of the medical bills.