It was announced on Saturday that the former Tottenham, Wolves and Bradford defender had died after a long-term illness at the age of 36.
After watching his Motherwell side beat Celtic 2-0 at home in the Clydesdale Bank Premier League this afternoon, McCall revealed his sadness at hearing about the death of Bradford-born Richards.
"It is an absolute tragedy," McCall told Press Association Sport. "I got few texts on Saturday telling me about the sad news of Dean's death through illness.
"I didn't realise he had a long-standing illness and it came as a great shock. I had Dean in doing a little bit of coaching at Bradford a few years ago.
"He was a first-class professional as a player but a fantastic guy off the park as well and I was really sad to hear the news. He will be a great miss."