In Chapter 7 of A Separate Peace, Brinker stages a "mock arrest" of Gene as they go to the Butt Room, a basement area where the boys smoke.  Seizing Gene's neck, and pusing him into the Butt Room, Brinker "announces,"

Here's your prisoner, gentlemen...I 'm turning him over to the proper authorities.

One of the boys asks what the charge is, and Brinker replies,

Doing away with his roommate so he could have a whole room to himself.  Rankest treachery....Practically fratiricide.

Gene shakes himself free from Brinker, who tells him he will have his day in court.  Gene then says,

Shut up!  I swear you ride a joke longer than anybody I know.

This statement is a mistake, Gene narrates becaus the radio suddenly became quiet and his voice rings out, "galvanizing them all."  One boy asks, "So you killed him, did you?"

Brinker qualifies his statement:

Well, not actually killed.  Finny's hangin between life and death at home, in the arms of his grief-stricken old mother.

Gene tries to diffuse the situation by saying he just a "little pinch of arsenic in his morning coffee."  Brinker will not let Gene out of the situation by declaring "We know the scene of the crime."  Again Gene tries for humor, using a "funny French pronunciation":  "Yes, huh, yes there was a small, a little contretemps at the tree."

When a young boy asks Gene to tell them everything, there is an "unsettling current in his voice, as though he believed everything," so Gene gains confidence and continues his fabrication, saying he stole Finny's money, cheated on his entrance test, blackmailing his parents; then, he made love to his sister....,but when he can easily slip in the truth and have it disbelieved, Gene's throat closes on him:  "I could never say them, never.

I swung on the younger boy. 'What did I do then?' I demanded.  I'll bet yhou've got a lot of theories.  Come on, reconstruct the crime.....

His eyes sung guiltily back and forth, 'Then, you just pushed him off, I'll bet'

After getting the boy to say the truth that he cannot, Gene has effectively defeated the crowd.  However, as they go up the stairs one boy remarks,

Funny, he[Finny] came all the way down here and didn't even have a smoke.

What begins as a mock arrest almost becomes a trial for Gene.  In fact, it has for Phineas.