How did Virgil Tibbs find out Ralph was the killer in In The Heat Of The Night?

In "In the Heat of the Night," Virgil Tibbs discovers Ralph's guilt through a combination of investigative intuition and evidence. Tibbs notices inconsistencies in Ralph's alibi and uncovers the critical detail that Ralph's car was at the scene of the crime. Additionally, Tibbs's sharp observations lead him to connect Ralph to the victim, ultimately revealing him as the killer. This culmination of clues and logical deductions allows Tibbs to confront Ralph and expose the truth.