Baton passed. I'll first explain: Infinite Crisis is an incredibly stupid and sprawling mess that I've only read parts of, so this will be kind of incomplete.
Infinite Crisis is a morass of somewhat interconnected storylines that will supposedly change the DC universe forever, just like the last five did. Identity Crisis was the first of these, and revolved around the murder of Elongated Man's wife, Sue. In the course of the investigation, it came out that Dr. Light (the evil one, not the heroic Japanese one) had raped Sue during Elongated Man's time in the Justice League, and that the Justice League had performed magical brainwashing on him and several other villains. On learning this, several members of the League left. Eventually Sue's murderer turned out to be The Atom's ex-fiancee Jean Loring, who had decided that if a superhero's wife died, they would all pay more attention to their loved ones.
Meanwhile, in another storyline, Blue Beetle discovers that there is some kind of sinister project underway called "OMAC" involving spy satellites and nanite-colony supersoldiers. Due to his reputation as a loser, his repeated calls for assistance from other superheroes are ignored. He is then shot and killed by former Justice League backer Maxwell Lord, who has been retrofitted with a new personality by someone who didn't think the old one was eXtreme enough. He now hates all superheroes, has regained an amplified version of the mind-control powers he once possessed, and is apparently a member of the superspy organization Checkmate. He mind-controls Superman, and is killed by Wonder Woman. There is also some kind of connection between the OMAC project and Batman's company, Wayne Enterprises, but from here on in my knowledge is mainly hearsay, so it's kind of fuzzy.
Apparently the OMAC supersoldiers go berserk and kill Rocket Red, presumably carrying out DC editor-in-chief Dan Didio's mission of vengeance against the early-90s run of Justice League written by Keith Giffen, a kind of "superhero sitcom" in which everyone who has been killed so far were given major roles.
Meanwhile, in a plot that may or may not have anything to do with anything else, third-string villain Cat-Man along with a lot of other mediocre supervillains I don't even remember has formed a group called Villains United that go around killing people. So far, Deathstroke The Terminator, who is currently not very popular and is therefore being written as a villain, has killed Firestorm, Uncle Sam, The Black Condor, The Phantom Lady, and The Freedom Fighters.
Also, Power Girl has received her fourth secret true origin, establishing her to be Superman's lost cousin from another dimension, although still distinct from Supergirl, who may or may not be Superman's cousin from this dimension, but certainly likes to kill people, perhaps as a result of being introduced as a new character and then killed about four or five times in the past fifteen years. Also also, the wizard Shazam, from whom Captain Marvel derives his powers, has been killed by someone, I don't really care much at this point, and his Rock Of Eternity has shattered into myriad mystical artifacts which rained down on Gotham City.
There's probably more but this is about the limit of my knowledge and I have no real desire to actually read more at this point.