The call that started it all

On the 10th of February in 1993, things seemed usual. Linda went to work. Then at 4:45 P.M., she received a call from Richard. He said he needed to go to the emergency room because he felt ill, but that he’ll wait for Linda to come home. When she arrived home, she was shocked to find their eldest son Matthew all alone by himself. Richard was gone.
No sign of him
She proceeded to call the hospitals to see if Richard had been to any of them. There was no sign of him leaving for good, because all of his belongings were still in the house, even his passport. He even left his coat, although it was cold out.