William McCabe, the father of murder victim Johnny McCabe, suffered a heart attack Monday morning and was taken to Lowell General Hospital Saints Campus.
According to his daughter, Roberta Donovan, McCabe is also being treated for kidney failure.
McCabe, 85, had not been feeling well, and left the murder trial of Michael Ferreira early last Wednesday and he was not in the courtroom for closing arguments on Thursday.
On Friday, jurors returned a verdict of "not guilty" for Ferreira on 1st and 2nd degree murder charges in connection with the death of Johnny McCabe.
Donovan has said the verdict has been very hard on her parents, her sister and herself.