An ex-girlfriend of a man accused of murdering Hartlepool mum-of-three Kelly Franklin suffered from mood swings, a court heard.
Torbjorn Kettlewell, 30, is accused of stabbing the mother of his children to death on August 3 last year in Hartlepool.
A jury at Teesside Crown Court heard Kettlewell had two girlfriends at the time of the attack on Ms Franklin, from whom he was estranged.
They were Julie Wass, who is also charged with murder, and Corrine Hunter, a woman he spent some time on the day Ms Franklin died.
Ms Hunter said Kettlewell had rang her that day to say he had 'hurt Kelly', and that he wouldn't be seeing her again.
Under cross-examination from Richard Wright QC, defending, Ms Hunter said Kettlewell could be unpleasant.
"He could also be kind and considerate," added Ms Hunter. "His mood could shift quickly.
"I thought he was suffering from depression, but he was never violent towards me.
"I never thought he would kill or hurt Kelly."
Ms Hunter said Kettlewell appeared at times to be mentally unstable, but he was also intelligent, and he gave her the impression he knew what he was doing.
The jury also heard from Deborah Bewick who used to work with Julie Wass in the outpatients' department at Hartlepool General Hospital.
"We were often on the same shifts," said Mrs Bewick."We would talk at lunchtimes.
"Julie told me she was unhappy in her marriage.
"She was in a very low mood in the weeks leading up to Kelly's death.
"Julie told me she was having an affair with Ian which started after he and Kelly lost the children when he accidentally shot the youngest one with an air riffle.
"I met Ian at the hospital one lunchtime, he was there with Kelly, and I felt uncomfortable because I knew he was seeing Julie.
"I didn't think he wanted to hurt Kelly, but he did want to hurt the social worker who had removed the children."
Mrs Bewick said Wass had sent her a text message after Ms Franklin was killed.
"The message said Ian had killed Kelly," said Mrs Bewick.
"Julie said she had seen him do it, she said the police were there, and she wouldn't be coming to work."
Mrs Bewick said Wass told her later she had seen Kettlewell banging on Ms Franklin's door in Kipling Road, Hartlepool, on the night of the killing.
"Julie said she had offered to take him home," Mrs Bewick added.
"As they were leaving the area, Ian had spotted Kelly and jumped out of the car and attacked her.
"Julie said she drove off, but stopped the car to vomit.
"Ian got into the car and told her to drive him away.
"Julie said she was scared, Ian looked like he had taken something."
The court heard earlier Wass is alleged to have taken Kettlewell in her car from the scene of the killing to woods near Trimdon.
Kettlewell, of Oval Grange, Hartlepool, denies murder on August 3.
Wass, 48, of Kipling Road, Hartlepool, also denies murder. She admits assisting an offender.