I mean technically, it's considered murder right?? Since dignam was off the force and even though he has proof that proves Matt Damon is the rat, there's no justifying in shooting him..I think he would later take Costigan's evidence and expose Sullivan, still would he face any kind of punishment at all for killing Sullivan??
I don't think Dignam intends on getting caught. If caught he could be arrest and prosecuted for murder. It was premeditated - it wasn't self defense - it was clear cut murder.
He did plan it well though. He was wearing plastic over his shoes to cover his tracks. He also was wearing plastic gloves. Though he could still maybe be prosecuted for it later, I guess.
My guess is he gets/has access to the surveillance recordings and releases them to the media after Sullivan's death.
This would create intense embarrassment for the State Police and open the possibility to many other potential conspiracies, taking Dignam off the spotlight.
Without doing this, Dignam might have been seen as a potential rival and possible suspect. Although I suspect he did the job well enough to avoid any evidence linking him to the crime and is more or less into the wind.
perhaps he was also influenced by what happened to both Queenan and Costello when they tried to go about it in the legit way. Plus Sullivan, already the golden boy in SIU before, was now even more of a hero in that department after he'd taken down Costello (from their perspective). His status there, a lot of colleagues in influencial positions in SIU would maybe close ranks around him, and as you say, it would also be embarrassing for the department to admit that their rising star had turned out to be Costello's biggest mole, so it would be in their interests for it to go way. This, combined with the way Sullivan had managed to weasel his way out of any previous suspicion and, either through Sullivan himself or from other moles that Costello had planted in the department, had anybody going after him murdered, would make it difficult and extremely dangerous for Dignam to tackle him through SIU - in fact it's clear from his interactions with Alec Baldwin's character (i forget his name) that Queenan was the only person he trusted and was comfortable working with, so he wouldn't even have known who to bring in to help him with this.
Hence he worked alone and exacted his own justice.
Baldwin's character (Ellerby) seemed a bit of a complacent careerist, playing golf, advising Sullivan on how to get ahead in social terms. talking about "marginally disrupting" crime in the city (maybe realistic, but not suggesting he takes it altogether seriously). And he didn't seem concerned about the idea of a mole (though he might not have been told). Did he actually accomplish anything in the movie? No wonder Dignam didn't trust him.
As a former undercover cop he would likely know how to make it look like a gang hit. Sullivan might look like a dead hero but the shrink and Dignam would know the truth. Or if Dignam is really embittered he might release the tapes and shame the police department.
Dignam was never off the force. He was suspended with pay. With Sullivan gone perhaps he works his way into his old job or takes over for Queenan. Perhaps he plays a role in investigating Sullivan's murder and can easily guide the investigation away from him.
With the revelation that Sullivan was working for Costello that opens up a whole bunch of potential killers in Costello's crew and from Providence.
So what? The prick deserved it. Not only did he murder (and allow murder at the behest of Costello) but he flat-out murdered Costello because he found out he was an FBI informant. Goddamn pansy couldn't get his dick hard to plow patch on his live-in shrink either. He's worthless. Way better off with his brain matter splashed on his nice white door. I wonder if he shit his pants too.
It's interesting that Dignam had done "extensive" undercover work. With his temper and aggressiveness, how long would he last? Billy had a bit of a temper too but he could rein it in - he didn't tend to be the aggressor.
that would be a nice touch - just as the department had Sullivan looking for Costello's rat ("I have to find myself"), they'd have Dignam looking for Sullivan's killer
and just to add, "Dignam was never off the force. He was suspended with pay" - glad someone else has made this point. I think it's deliberately left vague - Sullivan tells Costello that Dignam had quit "put in his papers", then tells Costigan that he's taken a leave of absence. Well, he did say he was pretty good at lying.
More crucially, on the rooftop Costigan's yelling to trooper Brown "where's Dignam? I told you to bring Dignam" - quite what communication there had been between these 2 before the rooftop meeting isn't clear, but I'd like to think that when this was brought up, if Dignam really had left, Brown would have mentioned this to Costigan.
Ellerby says “world needs plenty of bartenders, 2 weeks with pay” which means he gave Dignam 2 weeks notice. Dignam quit, but could’ve been rehired at some point
Oh how dozy am i?! I always thought when Alec Baldwin says "2 weeks with pay" he's referring to taking a leave of absence. I didn't even think about it being for his notice period until i just read your reply. That does make more sense that way.
And technically he would be serving this notice period when Sullivan tells Costigan that Dignam's taken a leave of absence.
Thanks
Given Ellerby introduced Dignam as having done "extensive" undercover work and they had their little cuss-filled macho back and forth, there seems to be some respect there. Dignam might indeed have come back. Dignam was a hothead but presumably a good worker - maybe this has happened before and he just needed time to cool off.