Shocking moment officer punched unarmed suspect in the face six times before tripping over his heavily pregnant wife 

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The Denver Police are now under investigation by the FBI for brutality, after a video surfaced online showing an officer punching an unarmed drug suspect six times in the face and causing the man's seven-months-pregnant wife to trip and fall on the ground. 

The video obtained by Fox Denver is also raising questions about whether the officers involved in the incident violated cell phone search laws, since the witness claims they grabbed his tablet and tried to delete the clip - though they would need a warrant in order to take any of his devices. 

Bystander Levi Frasier was driving to work on August 14 when he saw an incident escalate between a man and a few cops and undercover officers, so he pulled over, took out his tablet and started recording the scene. 

Police say the incident started when suspect David Nelson Flores noticed plainclothes officers approaching him, and he tried stuffing a white sock full of what was believed to be heroin into his mouth.

WARNING GRAPHIC IMAGES: Scroll down for video 

Brutal: A video has surfaced showing the moment a police officer punched a suspected drug user six times in the face during an arrest last August 

Injured: Suspect David Nelson Flores (pictured) sustained several injuries to his face and head during the attack 

Flores was then tackled to the ground as the undercover cops, and back-up officers Charles Jones IV and Christopher Evans, arrived on the scene and tried to pry the sock out of the mans mouth.

When Flores refused to spit up the sock, Officer Charles Jones IV punched the suspect six times in the face, his head bouncing off the pavement as he receives the blows. 

'Those were the hardest punches I have ever heard,' Frasier said. 'I’ve seen some people get punched in the ring and on TV and whatnot, but the sound of those resonating, I mean, it was scary. I’ve never heard anything louder than that and I used to cage fight for quite a while and I’ve never seen punches harder than that.' 

And that's not all. Jones proceeded to trip Flores' girlfriend, 25-year-old Mayra Lazos-Guerrero , when the seven-months-pregnant woman approached the tustle and started yelling at them to stop hurting her boyfriend. 

Charged: Flores (left) and his girlfriend 25-year-old Mayra Lazos-Guerrero (right) face several charges related to the incident, but were no shows at their last court date

Shove: The video also shows how one of the officers pushed Guerrero when she approached the group, telling them to stop hurting her boyfriend 

Expectant: Guerrero was seven-months-pregnant when she fell to the ground in the incident

Guerrero falls to the hard cement, landing on her  stomach and face and is seen yelling out in pain, clutching her bump.

However, the officer has explained his use of force, saying he was trying to retrieve the heroin and also prevent Flores from clutching. As for Flores' girlfriend, Jones says he thought she was going to kick him. 

Frasier doesn't think she her behavior was threatening: 'She was screaming like, "What are you doing. Let him go! Let him go! Stop hurting him! What are you doing?" She was just concerned for him. You could clearly hear that and as she got closer.'

Fox Denver also obtained pictures of Flores' wounds as he was being transported to the hospital. The graphic images show his battered head, bloody from being hit on the pavement as well as bruises and cuts all over his head.

But Mark Carlson, a former detective hired to analyze the video for Flores' potential criminal case, says he believes the officers went over the top in their use of force.

Illegal search? Witness Levi Frasier says police officers grabbed his tablet after the incident and then deleted the video. He was able to save the clip though, since it was uploaded to his cloud before the device was taken by authorities 

'There’s no obvious and immediate threat of a weapon,' Carlson said. 'I just don’t see how either swallowing evidence or they’re worried about him choking is justifying that degree of force. I mean, you’re risking, "We don’t want you to choke, so we’re going to fracture your face instead?"'

The FBI Public Corruption Unit is now working with the internal investigators with the Denver Police to see whether the determine whether the incident is a case of police brutality.

The officers behavior after the incident is also under investigation by the FBI, for possible breaches of cellphone search laws. 

Frasier says in the aftermath of the fight, officers approached him and coaxed him to hand over his tablet, even though he told them that they needed a warrant to do that. When they handed the tablet back to him, the video had been deleted, but he was able to salvage the clip since he had already been uploaded to his cloud. 

Flores was charges with resisting arrest, and two felony drug charges, while his girlfriend faces charges of obstruction, drugs and child abuse (there was a child in the car when the arrest happened). 

Neither appeared at their most recent court appearance, and are being asked to turn themselves in.

Denver Police Commander Matt Murray responded to the video with a statement saying: 'We are not covering anything up. There is no cover up whatsoever, so let me just put that to rest. That’s irresponsible and baseless.'