Ralph is a man who works at DeLuca Studios, an art studio owned by Fred DeLuca. Ralph is shown a good painter as it is known that some of his paintings were at museums. Somehow, Ralph saw Sylvia Moon's work and knew the "signature" of Sylvia on her paintings, a crecent shape cut in the corner of her paintings with a palette knife.
Ralph is approached by Detective Goren, who asks him to take a look at some of th paintings at RSL Gallery. Ralph looks at the painting and he states that the first painting was one of the best works of forgery he has seen on a while. Ralph asks about the materials used in the painting and Detective Goren gives the list of materials used in the painting and says that the painting was in a art museum. Detective Goren mentions how some of Ralph's paintings are in museums but Ralph nor Detective Goren ever says what museum the paintings were at. Ralph looks at the painting's right hand corner and notices the "signature" of Sylvia and he looks at another one of the paintings. He sees the same "signature" and points it out to Detective Goren and says that it was the signature of Sylvia Moon.
With this information from Ralph Detective Goren, along with his partner, Detective Eames were able to find Sylvia and use her as a witness for a period of time but they realize upon ariving at the murder scene that she had murdered her college roommate Zoey Payton and Bernard Jackson and Anne Ellis. (CI: "Art")