Dr. Sorenson is member of Muirfield who is Claire's partner. Dr. Sorenson killed Alex Salter's journalist friend when he started digging into Muirfield, and coerced Evan Marks to join Muirfield. He was killed in the explosion of the chemical lab set by Vincent and J.T. to fake the Vigilante's death. He enticed Evan into joining Muirfield by offering him a position because of his expertise; Evan turned over his research to Muirfield, but they backed out of letting him join. When he argued with them, Agent Kyle and Sorenson threatened him with a gun, forcing Evan to back off.
Claire meets Dr. Sorenson at a restaurant. He asks her how things are going with Evan. She tells him that Evan got too close to Vincent. She informs Dr. Sorenson that she corrupted Evan’s lab samples. Dr. Sorenson reminds her to maintain her cover and not expose that she works for Muirfield. (On Thin Ice )
Claire meets Dr. Sorenson at a park bench. She informs him that Evan notices that she is distracted and he is getting closer. Dr. Sorenson says they have another lead but no details because Vincent took out the entire team on it. Dr. Sorenson gives Claire a picture of Alex saying that she could be protecting Vincent. Dr. Sorenson informs Claire that he took care of the journalist that Alex talked to, so now he wants Claire to take out Alex. Later, Dr. Sorenson follows Alex on a bus. (Trust No One )
Evan meets with Kyle and Dr. Sorenson at Muirfield. Evan hands over his research on “the cross-species creature” because Dr. Sorenson promised him a position and that they would find it together. When Evan threatens Kyle, Dr. Sorenson pulls a gun on Evan and tells him to leave. (Any Means Possible )
Dr. Sorenson meets Evan in the morgue. He tells Evan, “You got onto something that’s of interest to us.” Evan advises Dr. S about attacking him in a police pricenct, Dr. Sorenson says that Claire seems to have given Evan “the wrong impression about us.” He is surprised with how much Evan has figured out about cross species DNA on his own. He says Evan “would be an asset” to Muirfield. He profiles that Evan became a medical examiner to put away dangerous things, like the “creature ”. He hands him a business card with only a phone number on it (212-555-0183). Evan later uses the card to meet up with Dr. S at an undiscolosed Murifield site. (Tough Love )