Well, shit. I went back and reread much of this thread for past ideas on how I had considered handling the cardinal killings/suicides to see if I can improve the detective half of this story. Not nearly enough tension at present to keep me interested. Turns out I already pretty much considered half a dozen ways of doing things, which resulted in numerous versions of scene 1.2 (first cardinal meets the Antichrist). The current approach evolved from the other five I punted. Seemed like a good idea at the time.
One new option is to pose all of the dead cardinals crucifixion-style, hanging from high on a wall. Cardinal Vitale would be nailed above the high altar. Maybe they even died from being crucified? Lets face it, these cardinals are not in great health to begin with. Death by crucifixion is probably the only violent form of death that Catholic readers might tolerate. It begs the question, though, how the Antichrist got the cardinals up high on a wall by himself. He's very powerful, but nailing someone against a high wall probably requires more than one killer, and I don't want to introduce more demons if I can avoid it. The focus should be on the AC.
I also still have the option of having them die of sheer terror. That was an option I considered at one point. Not sure how to build on that, though.
Manner of death only buys me maybe 5% more tension. It's the slow pace of the investigation that's killing me. Problem is, if the killings pile up quickly, then all of Rome will know about it and a huge police task force would be set up to investigate the deaths. I don't have enough info on Italian police procedures to do the task force, unless I use the idea of a special dedicated tactical team from the outset (i.e., made up any way I like). Kind of like Men in Black, minus the humor.