A 51-year-old man who is accused of turning off the air supply of a teenage lobster diver is speaking out a day after he was charged with attempted second-degree murder.

Michael Simpson denied all the allegations against him in an interview with “Good Morning America” that aired on Friday.

“It’s all lies, it’s simple. It’s been a devastating few days. It’s absolutely untrue,” Simpson told ABC News’ Victor Oquendo.

Simpson, a former Florida boating safety task force member, was allegedly involved in a dispute over a fishing spot in South Florida on July 29, in what is known as “lobster mini season,” a time when recreational fishermen can catch lobsters before commercial fishers. He is accused of boarding a boat and shutting off the oxygen supply of a teenager who was diving at the time.

According to an arrest affidavit from the Miami-Dade Sheriff’s Office, 18-year-old Hunter Coffer was using a brownie third lung, or a floating air tank, attached to a long hose. The affidavit claimed Simpson, traveling by boat, approached Coffer’s boat at a “high rate of speed circling [the] vessel several times” before he swam “over to the air supply unit and intentionally [turned] it off,” in an incident partly caught on camera.

Police say Coffer was pulled to safety by his boat partner, who told police Simpson fled the scene and the boy was gasping for air. 

Simpson was arrested this week and charged with attempted second-degree murder.

He appeared in a bond hearing at a Miami courthouse Wednesday. “This is a very serious matter that somebody would try to turn off somebody’s air tank while they are swimming, diving,” the judge told Simpson.

Simpson told “GMA” he never threatened to shut off the teen’s air supply.

“That is no, that is 100% no,” Simpson said.

Simpson also said he and his sons, who were with him, did not flee the scene and slowly drove to another dive location about 100 yards away.

“To portray myself as this animal or murderer that would turn off air for no reason, no motivation, the explanation has been a 100% lies and it’s been devastating,” Simpson added.

Simpson’s attorney said he will plead not guilty and his case has now been transferred to the Miami-Dade State Attorney’s office. A court date has not yet been set.