Continuity mistake: When Lynette sits down next to Claire on the bench at the park, Claire is wiping her hands with a tissue. Claire is not wiping her hands in the next shot, but in the shot after that, she is.
Other mistake: Bree is drinking wine with Karl, but before in other episodes and season and episodes and seasons after, she sternly says she does not drink because she was an alcoholic.
Answer: He was investigating the lead not the case.