Stein, 33, is standing trial for murder in the New South Wales supreme court over the death of schoolgirl Charlise Mutten, whose body was found in a barrel by the Colo River in the Blue Mountains on 18 January 2022. He has pleaded not guilty.
Mutten was in a relationship with Stein at the time and the pair had planned to get married, the jury previously heard.
Police approached Sweeney afterwards to ask if Stein had said anything to her during the interview, which she described as highly unusual.
Stein gave his mother Annemie the same account in phone calls from prison, which were recorded and played for the jury.
Stein claimed in the recorded phone call that Mutten had put the barrel with the remains on the back of the ute without his knowledge and only informed him of it later while he was out driving the vehicle.
The trial continues.
