The fiancé of Jake Anderson-Brettner told a Supreme Court jury in Launceston that alleged murderer Jack Harrison Vincent Sadler lied to her on the night he went missing.
Katlyn Roney said she had gone to Mr Sadler's Riverside home about 2am on August 16, 2018.
Ms Roney was giving evidence in the trial of Mr Sadler, who has pleaded not guilty to Mr Anderson-Brettner's murder.
She said that she woke up to find Mr Anderson-Brettner had not arrived home.
When she first arrived at Mr Sadler's residence no one was home, but floodlights were on.
She waited for 20 minutes until Mr Sadler arrived.
She said Mr Sadler told her Mr Anderson-Brettner had not come to his house and that he had gone out looking for him.
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"I just said I didn't believe him," she said.
"He said 'why because me and Jake don't have any issues'."
She said Mr Sadler stood with his arms crossed moving his weight from foot to foot.
She said Mr Sadler was wearing saggy track pants compared with his usual "nice expensive tracksuit with a gold chain".
"I told him he was a liar," Ms Roney said.
Under cross examination from defence counsel Greg Richardson, Ms Roney denied Mr Anderson-Brettner was involved in drugs.
Mr Richardson asked her about several cars that Mr Anderson-Brettner, an apprentice butcher, owned.
Day two of the trial before Justice Robert Pearce continues.
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