Alta Von See (Marin Ireland) is the main villainess from "Evidence of Things Not Seen," the second episode of Elementary's fourth season (airdate November 12, 2015). She is a scientist at DARPA, and was actually the next in line for the head position, held by Samuel Meher.
Looking to climb the corporate ladder, Alta invaded a lab test and killed scientists Gail Sarkisian and Frank Weller, as well as test subject and grad student Ollie Tate. She used a sonic-pressure shield to debilitate her intended victims before shooting and killing them. Alta's murderous plan was to cause a scandal at DARPA which would result in Meher being ousted; however, there was a fourth victim--in the form of Weller's lab rat, which died due to asphyxiation. As shown in the flashback, Alta was standing properly while committing the murders, but she was using a cane on her right side--assuming that the shield's affects slightly damaged her. Alta was subsequently arrested for the murders.
- Marin Ireland also appeared on Unforgettable as the villainous Sarah Green.