Continuity mistake: Right before Ben jumps off the cliff, he drinks a small cup of coffee and places it back on a saucer that Jonathan is holding. When the shot cuts, the saucer is still visible in Jonathan's hand, but the cup cannot be seen on it. The cup then reappears in the next shot.
Answer: In Frederika's bedroom Clarice sees the dress being made and recognises that the pieces of material are the same shape as the pieces of skin missing from the victims' bodies. In the bank, where Clarice meets Frederika's friend, Stacy tells her the address of 'Mrs Lippman' whom Frederika used to work with. Presumably Buffalo Bill is related to, or is, Mrs. Lippman since that is where Clarice finds him.
jle
He's not Mrs Lippman. He did, however, kill her. As Clarice chases him through the cellar, the woman's decomposing body is in a tub.