The police open an investigation and determine that Anya's fingerprints on the bottle and glass were indeed planted. Lisa is placed under arrest based on a statement from Mrs. Roper, who had seen her handle the items shortly after Anya's death and had also seen her and Karl embrace.
The investigation revealed that Anya's fingerprints were planted on the bottle and glass, leading to Lisa's arrest based on Mrs. Roper's statement. This suggests a potential motive for Lisa's involvement in the crime.