When Jane goes to switch out the painting from Alov he runs away with the fake instead of the real one.
It is never explained why Rob Wallace, the artist who painted the two copies of the The Moro, draws his firearm and threatens Van Pelt. As confirmed in the following scene, Mr. Wallace was not aware of Harry Lashley's murder, or that Harry Lashley was involved in the theft of the painting.
Even if he did not believe her cover story, Mr. Wallace had no reason to think that Van Pelt was a threat to him. His suspicion of Van Pelt is seemingly random and he threatens to shoot her unprovoked.
Even if he did not believe her cover story, Mr. Wallace had no reason to think that Van Pelt was a threat to him. His suspicion of Van Pelt is seemingly random and he threatens to shoot her unprovoked.