# Inspector Tanner Becomes Convinced explained — The Ponson Case > Chapter companion for The Ponson Case by Freeman Wills Crofts. ## What happens Inspector Tanner reviews the evidence against Austin Ponson, considering motive and opportunity, but becomes convinced that the alibi is genuine and that Cosgrove Ponson is the real murderer. He interviews Lois Drew to confirm Austin's alibi and decides to investigate Cosgrove's involvement. ## Themes in this chapter ### Justice and Investigation Tanner methodically re-evaluates evidence, tests alibis, and shifts suspicion based on logical deduction. ### Wealth and Motive The inheritance of £150,000 and Cosgrove's additional £30,000 provide strong financial motives for murder. ### Deception and Identity The hoax note and planted evidence suggest a deliberate attempt to frame Austin, highlighting deceptive identities. ## Character check-ins ### Inspector Tanner Reviews the case, becomes convinced of Austin's innocence, interviews Lois Drew, and decides to investigate Cosgrove Ponson. ### Austin Ponson Suspect in his father's murder; Tanner considers evidence against him but later believes his alibi. ### Sir William Ponson Murder victim; his strained relationship with Austin and will are key to the motive. ### Cosgrove Ponson Cousin of Austin; Tanner suspects him of murder and framing Austin for financial gain. ### Lois Drew Austin's fiancée; Tanner interviews her to confirm Austin's alibi and finds her credible. ## Key lines > He realised that the lawyer’s communication contained food for thought. Certainly a lot of the information he had gained seemed to point in a rather unmistakable way to Austin. Tanner acknowledged that the lawyer's message gave him much to consider, as much of the evidence strongly suggested Austin's guilt. _Tanner reflects on the accumulating evidence against Austin._ > If his father should die without altering his will, it would mean £150,000 to himself. £150,000! Quite a respectable sum of money! If Sir William died without changing his will, Austin would inherit £150,000, a substantial fortune. _Tanner considers the financial temptation for Austin._ > The man who made the plant was familiar with Austin and his affairs. Who, of those who knew the affairs of both Austin and Sir William, had an interest in the latter’s death? The answer was not far to seek. One such at least was Cosgrove Ponson. The person who set up the false evidence knew Austin well. Among those familiar with both Austin and Sir William, Cosgrove Ponson had a clear motive for Sir William's death. _Tanner deduces that Cosgrove is the likely culprit._ > I am sorry to say we don’t exactly understand how Sir William died. There is a doubt that it may have been suicide or even murder. Tanner admits to Lois that the cause of Sir William's death is uncertain, possibly suicide or murder. _Tanner reveals the uncertainty of the case to Lois Drew._ ## Links - HTML: https://www.betterreads.online/discover/the_ponson_case_se/chapters/v-inspector-tanner-becomes-convinced - Book: https://www.betterreads.online/discover/the_ponson_case_se - All chapters: https://www.betterreads.online/discover/the_ponson_case_se/chapters