Murder accused Angela Newlands appeared “genuinely shocked” when she heard Annalise Johnstone was dead, the High Court in Livingston heard.
The 28-year-old gave a statement to police after Jordan Johnstone reported his sister missing early on May 10.
Annalise was found dead in May last year.
Newlands told investigators she had gone with Johnstone and her four children to stay with Annalise in Ardrossan on May 7.
She said Annalise had been moody and believed she was not welcome in the Travelling community because she was gay.
“I noticed her mood swings,” she told police. “She was up and down, and she was always on the phone.”
She said Johnstone and his sister had come to her mum’s home in Inchture on the evening of May 9.
“We tried to convince her to stay,” she said in her statement. “But they left at about midnight.
“He came back at 1am. He said he dropped her off at the top of his uncle’s street. Jordan said Annalise was refusing to come back (to Inchture) as she was getting drugs.”
She said she woke the next morning to a series of phone calls from relatives of Johnstone, asking if they had seen Annalise.
The court heard Johnstone had called 101 to report Annalise missing, while they went for food at McDonald’s at Broxden in Perth.
In her statement, Newlands said Annalise had told her she was gay and bipolar on the second occasion they met. She said she had formed a new family with a church group in Ardrossan.
Detective Sergeant Beverley Simon, who had taken Newlands’ statement, told the court she returned to Inchture on the evening of May 11 and told her Annalise was dead.
Asked how she reacted, DS Simon said: “She looked genuinely shocked.”
The court earlier heard Johnstone had punched Newlands in the face in a row the day before Annalise died.
Witness Tracy Brown said Johnstone had arrived at her home in Ayrshire looking for his cousin.
The court heard Newlands started sounding the horn in the car outside and the pair got into an argument and started hitting each other.
Under cross examination by Newlands’ counsel Mark Stewart, Brown accepted she had given a statement to the police saying she only saw Newlands being hit.
She told officers: “He punched Angela right in the face. The sound it made was sickening.”
Jordan Johnstone and Angela Newlands face a total of five charges.
It is alleged that on May 6 last year, at Bank Street, Coatbridge, they both assaulted Nadia Johnstone and threatened her with knives, repeatedly attempted to strike her on the neck with a knife, pushed her, threw liquid at her and punched her on the head, to her injury.
Johnstone is further accused of assaulting his sister Annalise Johnstone at Denholm Way, Beith, Ayrshire, on May 8 last year.
It is alleged he seized hold of her and pulled her from a Ford Galaxy car.
Prosecutors also claim that Johnstone stole a Hobby Caravan, and its contents, from Carmichael Place, Irvine, on May 9 last year.
It is alleged that on May 10 last year, both Johnstone and Newlands assaulted Annalise at the Maggie Wall Memorial on the B8062 Auchterarder to Dunning road, repeatedly struck her on the neck with a knife or similar weapon and murdered her.
Johnstone and Newlands are further accused of attempting to defeat the ends of justice on May 10 and 11, by (a) transporting Annalise’s body in the Ford Galaxy from the Maggie Wall Memorial and leaving her behind a stone dyke at the side of the B8062; (b) cleaning the Ford Galaxy; (c) setting fire to material, the nature of which is meantime not known to the prosecutor, and (d) falsely reporting Annalise as a missing person.