In In Cold Blood, what are Dewey's two different scenarios for the crime?

Dewey has two ideas, or
"concepts," about how the murders of the Clutter family were committed. The first
scenario is that a single murderer, likely a casual acquaintance of the Clutters, committed the
crime. That person likely knew that the family did not lock the doors and that Mr. Clutter slept
alone downstairs while the rest of the family slept upstairs. This person would have cowed the
family dog, Teddy, who was afraid of weapons, and he would have forced Mr. Clutter to tie up his
family at gunpoint. The murderer would have then bound Mr. Clutter and killed all the victims.
However, this theory has several holes. First, Mr. Clutter and his son would have struggled
against the murderer, and all the bodies were bound and trussed in exactly the same way (not, in
this scenario, by two different peopleMr. Clutter and the murderer).

The
second concept is that the murder occurred along the same lines but that there were two
murderers. The accomplice to the murderer tied and bound all...