The cops part to let Beard and Rebecca leave before entering. Joan recognizes both of them. They've worked cases with her and Sherlock on a number of occasions, and had always had a good rapport with them.

"Mr. Lasso," the older one said. "I'm Inspector McCoy, this is Inspector Rudd. We're going to be asking you some questions." He nods toward Joan. "Miss Watson. Mr. Holmes said you'd be here."

Sherlock probably sent them, and Joan silently thanks him.

"I'm glad to see both of you," she says, then turns to Ted. "I know them. We've worked with them before."