Cicero knew them all.

We cannot say that in this matter Caesar was guilty, but Cicero, no doubt, felt that Caesar's heart was with Catiline.

It was his present task so to thunder with his eloquence that he should turn these bitter enemies into seeming friends--to drive Catiline from out of the midst of them, so that it should seem that he had been expelled by those who were in truth his brother-conspirators; and this it was that he did.
He declared the nature of the plot, and boldly said that, such being the facts, Catiline deserved death.

"If," he says, "I should order you to be taken and killed, believe me I should be blamed rather for my delay in doing so than for my cruelty." He spoke throughout as though all the power were in his own hands, either to strike or to forbear.

But it was his object to drive him out and not to kill him.