I had the Lindt Cafe siege gunman in my sights and my finger on the trigger – but I never took the shot. Now I’m haunted by the horror that unfolded…

A former police sniper haunted by the Lindt Cafe siege nearly a decade ago still struggles with guilt for not firing when he had a clear shot at the gunman.

Mark Davidson was the senior sniper involved in the Sydney Lindt cafe siege on December 15, 2014, when Man Haron Monis stormed the CBD armed with a rifle claiming he had a bomb.

The officer, codenamed Sierra Three 1, was stationed opposite the Westpac building on Martin Place during the 16-hour standoff.

Of the 18 hostages in the cafe, Manis shot and killed Tori Johnson, 34, and Katrina Dawson, 38, was killed by police bullet fragments.

Davidson told 2GB host Ben Fordham on Tuesday that he is still overcome with guilt for not shooting Monis earlier during the siege and preventing the couple’s deaths.

Davidson said he had a clear image of Monis around 7:30 p.m., almost seven hours before police stormed the cafe.

Davidson explained that he, along with two other snipers, had a clear view of Monis at 7:30 p.m., almost seven hours before police stormed the cafe.

“Earlier in the escapade he (Monis) showed himself at the windows and doors… I was able to see him for about 10 minutes at about 7:30 p.m.,” Davidson said.

“I felt guilty for not shooting when he could have been shot clearly and easily without anyone else getting hurt.

“I feel guilty because I didn’t kill someone, I guess, it was feasible to do that and then potentially save everyone.

“We had ten minutes to get the best shot we could… and we could have ended the siege at 7:30 p.m. and not 2 a.m. when Tori Johnson and Katrina Dawson died.”

Davidson said he feared Monis was holding a “dead man’s switch,” which would have detonated a bomb if the person holding him was killed or released his grip on the device.

“We couldn’t really determine if he had one,” Davidson said.

‘I chose, we chose not to shoot him when we could see him at 7:30 p.m. We made that decision and we have to live with it.”

Of the 18 hostages in the cafe, Manis shot dead Tori Johnson, 34, and Katrina Dawson, 38, was killed by police bullet fragments (photo, paramedics working on wounded at end of siege)

However, Davidson claimed that police chiefs changed the game plan to deal with the hostage situation, after years of rehearsing one response only to trigger another at the last minute.

‘IIt’s a bit like a rugby league side practicing the set move for a grand final and practicing it all year round and then getting to the grand final,” Davidson said.

‘Then the captain said, “We’re not going to do the set move that we’ve been practicing all year. We’re going to do something new.”

‘They changed the goalpost at the last minute, when it matters most. We had the capacity to do the work that needed to be done.

“It was just the next level of management that didn’t let that happen.”

NSW Police previously rejected Davidson’s claim that he had a clear view of the terrorist and could have saved the hostages’ lives.

Police said Davidson’s gun would not have penetrated the window glass of the Westpac building and the window glass of the Lindt Cafe.

“Breaking the Westpac glass, i.e. creating a hole, and then shooting through it would have taken a lot of time and generated noise that could have been heard by Monis,” police said.

However, Davidson refuted the claims, explaining that he and his team had enough time to cut a hole in the window for a clear shot at Monis.

Police have dismissed claims by a Lindt cafe sniper that a hostage’s life could have been spared if he had been allowed to shoot.

Davidson said the Lindt Cafe siege was the “last straw” in a compilation of traumatic events that led to his medical discharge from the police force (pictured, flowers outside the Lindt Cafe)

Davidson said the Lindt Cafe siege was the “last straw” in a series of traumatic events that led to his medical discharge in 2017 after nearly 25 years on the force.

The former sniper suffers from PTSD, often has flashbacks of the murder of Tori Johnson, and has a troubling neurological problem that causes his arm to tremble.

He explained the guilt he felt after the Lindt Cafe siege and his PTSD inspired him to create his podcast ‘The Lawyer, the Sniper and the NSW Police’.

“(Guilt) was something I harbored initially and I went through that process,” Davidson said.

“The podcast was a good thing that came from my guilt. It inspired me to do something positive, to speak out and try to fix things so that the same mistakes that happened at the Lindt Cade siege don’t happen again.”

Davidson can be seen in the Guilt episode of SBS Insights on Tuesday at 8:30 PM.