topsie, that was what I tried to convey. Formal language: "It was I, they arrested me." Possible colloquial version: "It was me, they arrested me."

There are constructions in which language and logic disagree. Avoid them altogether if you need to be precise. In rare cases, ambiguities of language can be exploited for skillful rhetorics (alias lies). What John describes seems more like abused logic to me - I would not blame it on grammar at all.