Evans wrote: "I would like to apologise to the supporters of Harlequins on behalf of the club.
"Some of you will feel that manipulation of the substitution, uncontested scrums and sin binning rules are so widespread in the game that this case has been blown out of all proportion.
"Others will feel it a terrible episode which makes them ashamed of the club they love.
"Wherever you are on that scale of reaction, I am sure you would all agree that whatever goes on elsewhere we have got to accept that we have been found guilty of behaviour that cannot be accepted or condoned. For that we apologise to you unconditionally."
Evans also stressed the hope that Richards's career in the game would not be tarnished.
He added: "It was no surprise to me or the board that he [Dean] wanted to take full responsibility for events. One mistake, albeit extremely high profile, should not overshadow a career in which so much has been achieved."
The existing coaching team of John Kingston, Colin Osborne and Tony Diprose will remain in charge of team affairs and forward Nick Easter admitted the whole episode has left the club struggling to save their battered reputation.
He said: "It was a shock. Everyone has taken a hammering but it is still a good club to be at."
