Alex Moore (Melissa Joyner) is a villainess from "The Puzzle Palace," episode 10.17 of Blue Bloods (airdate April 3, 2020).
Alex Moore is the defense attorney for killer Jackson Wilks, who was arrested for killing Elliott Greene. During Wilks' interrogation, Alex stated to detectives Danny Reagan and Maria Baez that Wilks had never killed anyone, while Wilks added that Greene's death was due to drugs, and not the fact that Wilks bashed his skull in. To the detectives' surprise, the report backed up Wilks' claim, and a bigger surprise was that it was filled out by Megan Carson, who (as Danny pointed out) never made mistakes.
As Danny would later learn from Megan, the report was falsified, with Megan doing so after being threatened by Alex, as she was planning to have Wilks escape another murder charge. Danny and Maria interrogated Alex with the facts, with the villainess smirking over Megan revealing the truth, while also making a veiled threat against her. Afterwards, the evil Alex phoned Wilks and sent him to kill Megan, only for Danny and Maria to track Wilks and arrested him. Following Wilks' arrest, Alex was also arrested (off-screen) for her role.