Shane William Ryan claimed his unprovoked act of violence inside a Darwin gym was an accident. 

The CCTV footage told a very different story. 

On October 22, 2020, Ryan and another gym user were alone inside the Next Level Gym in Rosebery, a suburb just outside Darwin. 

The other gym user was performing a bench press – lifting two dumbbells while lying flat on his back on a bench. 

In footage shared by the NT Supreme Court, Ryan could be seen picking up a 20kg weight, walked towards the other gym user and dropping the weight directly on his face. 

The victim began bleeding immediately from his head where he would later be diagnosed with a fractured skull. 

Ryan, feigning an ankle injury, walked away from the victim before returning with a phone to call an ambulance. 

For months, the 33-year-old claimed it was an accident. But in the Supreme Court last month he changed his story. 

Shane William Ryan walking towards the victim with a 20kg weight in his hands. 

The CCTV footage has only recently been made public. 

Ryan was jailed for 19 months for an act that Justice John Burns said was "an extremely dangerous act" on a person "unable to protect himself". 

"At about 3.30am on (October 22, 2020), you and the victim attended the Next Level Gym in Rosebery," Justice Burns said. 

"At approximately 3.52am the victim was lying on his back on a flat bench conducting a dumbbells weight routine. 

"You picked up a 20kg plate and walked towards the victim. The CCTV shows you lurching towards the victim and dropping the weight onto the victim's head and chest area causing the victim to fall to the ground from the bench, bleeding from his head. 

"You feigned an injury to your left ankle before you stood up and walked away before returning to the victim and then calling an ambulance." 

The victim suffered a non-displaced left frontal bone fracture, a laceration above his left eyebrow which required five sutures, swelling to his face, headaches and chest pain, the Supreme Court heard. 

The moment Shane William Ryan dropped a 20kg weight on a gym user. 

In his victim impact statement, the victim said he needs ongoing medical treatment, has anxiety and must now take blood pressure medication. 

"You and the victim were previously amicable towards each other," Justice Burns said in sentencing remarks. 

"Indeed, you and he spoke in a friendly manner on 22 October 2020 before this incident. 

"Undoubtedly, the emotional effect of this incident on the victim has been heightened by the fact that your attack upon him was without apparent motive and in circumstances where the two of you had previously had amicable relations. 

"The act of dropping a 20kg weight onto the head of the victim was an extremely dangerous act. The victim was vulnerable as he was lying on his back and had weights in his hands. He was unable to protect himself. 

"He also had no reason to believe that you would attack him as you did." 

Justice Burns said it was "troubling" that Ryan had showed a "lack of an obvious motive". 

Ryan was jailed for 19 months. He is not eligible for parole until November 24, 2022, after serving a minimum of 10 months in jail. 

- by Rohan Smith, news.com.au