What troubles me isn't the odd idea from Askew that he would be blackmailed - it simply doesn't make sense that Davis would feel threatened by an unknown running against him - but the idea that Askew could be "outed" - there is no indication that he was in fact "in" (the closet, that is) so its seems like a nonsensical threat. Meanwhile, the newspapers seem to be dancing around wondering what their real relationship was - very veiled things like Davis was 41 and single (one paper notes he is handsome), Davis was 31 and single and handsome; they've had private meetings in Davis's office, as well as at least one meeting in Fort Greene Park. Um, how do I say this delicately? Fort Greene Park, at night anyway, is a known cruising spot. Of course, it is a nice park with a cool view of Manhattan, and by day and night, many folks go there (and both men live in the area) so that's not unusual for them to meet there. But doesn't it make more sense that Davis was the one being blackmailed? Davis is the one who had something to lose (his job, his reputation) whereas Askew did not. And the unsigned documents in Askew's possession? Perhaps Askew's attempt at blackmailing wasn't working, Davis was trying to appease/delay him without giving in to him, and refused to sign the documents; this angered Askew to the point that he pulled out the gun and shot.
I realize I watch a lot of Law & Order, but anyone investigating this must have thought of this scenario.