The Supreme Court trial of former detective Paul Dale has been told that key evidence heard during the case "blows away" Dale's defence that he cannot recall parts of his involvement with underworld figure Carl Williams.

Dale is accused of lying to the Australian Crime Commission in 2007 and 2008.

In his closing address, Prosecutor Christopher Beale SC, has asked the jury to consider why Mr Dale had an "ongoing, secret relationship with a notorious criminal."

Mr Beale says tape recordings of Dale speaking to Williams in friendly terms prove their involvement was far more extensive than Dale admitted to investigators.

Mr Beale says it is clear Dale had a strong motive to lie to the Crime Commission because he believed he was suspected of involvement in the murder of police informer Terry Hodson and his wife, Christine.

Mr Dale has chosen not to give evidence, but has denied the charges.