Lt. Col. Robin Deakins (LisaGay Hamilton) is the main villainess from "Give Me the Finger," episode 6.06 of Elementary (airdate June 4, 2018). She is a Lieutenant Colonel in the U.S. Air Force.
Deakins was looking to be moved up in rank, but became bitter when she was denied. When a disk that contained a recipe to print U.S. currency delivered to the military facility, Deakins took the disk (labeled Disk A), seeing it as a lucrative opportunity to gain millions she felt she was owed due to not being promoted. She needed to get her hands on Disk B, but she was running out of time due Ando Azuba, a member of a yakuza, was testing the security systems. Deakins had found a list of bases that bought crates that could contain Disk B, but seeing Ando as an obstacle, the evil Deakins murdered him and set fire to his home, while also taking possession of his prosthetic pinky finger.
Deakins' lack of her sense of smell led her to burn the apartment, but it also ended up revealing herself as the killer, as she let Ando's cooking burn during the murder due to her inability to smell it. Sherlock Holmes' summation provided the reveal, as he brought out a foul-smelling dish as part of his dining routine due to his post-concussion syndrome, with literally everyone reacting except for Deakins. The villainess arrogantly denied everything in the interview room, and after she left, Deakins went to a dojo owned by Go Shinura, another yakuza member. She was handed a fake passport with an alias, Laura Harrison, while also detailing her bitterness over the Air Force not promoting her. Deakins also gave Shinura the prosthetic finger, and it was there that Sherlock came out with Detective Marcus Bell, as it was revealed that she was being recorded. Though they didn't get a confession, the finger was enough to officially reveal her as the killer, and she was later handcuffed and arrested by Bell.