Probably you mean "a total of 23 wanted, former and suspected criminals died of heart attacks in the Tokyo metropolitan area"?
罪の疑いがかかっているだけの者 means "those who are just suspected", i.e., it suggests the possibility that they might not be even a criminal is higher than just 容疑者 "suspects". He needed to kill even those people.
I would translate 今分かっているだけで to "even limiting what we know now".