The Special Investigations Unit has concluded that there are no reasonable grounds to charge a London police officer after a man died following an altercation downtown earlier this year.

Officers were called to a fight outside Robinson Hall on Talbot Street in the early morning hours of Feb. 14.

Surveillance video obtained by CTV News showed that Aaron Ferkranus had struck and seriously hurt another man, and the man's friends retaliated.

At that point security guards intervened and were holding Ferkranus on the ground until police arrived.

Ferkranus struggled to free himself and security guards responded with several knee strikes to his legs and kept him pinned, at the same time guards became worried about the 26-year-old and checked to see if he was breathing while on the ground.

The SIU investigation found officers arrived to arrest Ferkranus for assault about 10 minutes after the altercation, but as they lifted him, they realized he was unresponsive so they called an ambulance.

Ferkranus died in hospital the following day.

An autopsy failed to determine a cause of death and more detailed medical examinations are ongoing.

The SIU concluded that the officer was not responsible for Ferkranus' death.