Daniel Boulton, 30, admits the manslaughter of his former girlfriend Bethany Vincent, 26, and nine-year-old Darren Henson but denies their murder.
Bethany and Darren, known to his family as DJ, were both found stabbed to death at their home in High Holme Road, Louth, shortly after 8pm on May 31.
Caroline Vincent, Bethany’s mother and DJ’s grandmother, today gave evidence on the third day of Boulton’s trial at Lincoln Crown Court.
Mrs Vincent gave her account from a witness box just a couple of metres from the glass panelled dock where Boulton listened to her evidence.
She described how her last contact with Bethany and DJ was in a bedtime Facetime conversation on the evening they were killed.
Asked by Katherine Goddard QC, prosecuting, how they seemed Mrs Vincent replied: “They were very happy.
“DJ had his Chelsea football top on, he was going to sleep in it.”
Mrs Vincent revealed Bethany was due to move house just four days later.
The jury heard Bethany began seeing Boulton in March 2019 and the relationship initially went well.
But the prosecution allege Boulton became increasingly violent towards Bethany and that following a complaint to police he was ordered not to contact her but “repeatedly broke it”.
The court heard Bethany’s previous relationship with DJ’s father, Kieran Henson, broke down when he was just a toddler, but Mrs Vincent described him as an “excellent dad” who would see his son on weekends and in the holidays.
Mrs Vincent said Boulton initially “seemed a nice smart lad.”
The good period lasted for “some months,” until Bethany became distant and gave up her job, Mrs Vincent told the jury.
“She didn’t want me to go round as much,” Mrs Vincent added. “He (Boulton) was staying alot.”
Mrs Vincent said she began to notice other changes.
“He (Boulton) was always with her, we didn’t seem to get much time with her,” Mrs Vincent told the jury. “He was quite possessive over her.”
The jury heard DJ was diagnosed with autism when he was two-and-a-half years old. Mrs Vincent said Boulton initially seemed fine with DJ but that changed later in the relationship.
“He (Boulton) said to us once he didn’t think DJ was autistic, he was just naughty.”
Mrs Vincent said the relationship became “on-off” and she would try to visit her daughter when Boulton wasn’t there.
“I knew he wasn’t treating my daughter properly,” Mrs Vincent told the jury. “He didn’t like me.”
Mrs Vincent added: “He was never nasty (about DJ), but he would say ‘DJ was picking on him.’ “
Mrs Vincent told the jury about one incident where her daughter called the police after moving to High Holme Road in Louth.
She described how during her visit Boulton gripped his fists and repeated “I am Dan.”
“Bethany ended up on the sofa. He (Boulton) was leaning over her. Bethany managed to get the phone and called the police.”
When asked to describe how Boulton was acting Mrs Vincent replied: “Angry, loud, nasty.”
She added: “I was scared the situation she was in.”
Following the incident Boulton was prevented from contacting Mrs Vincent and her daughter by an injunction, the jury heard.
Mrs Vincent said from that day she understood her daughter’s relationship with Boulton had ended, adding, “I got my daughter back.”
It is alleged that in the weekend before the stabbings, Boulton sent nearly 900 messages to Bethany on Facebook.
Ms Goddard said Boulton had also developed a “hatred” for DJ.
On May 31, the day of the attack, she said Boulton walked 28 miles from his home in Skegness to Bethany’s home in High Holme Road where he repeatedly stabbed her and DJ.
When police arrived at the property they found Bethany in the front room and DJ lying on the floor in his bedroom.
Ms Goddard said both had been stabbed and there were also “marks consistent with blunt force trauma”.
The court heard Bethany and her son had been due to move to an address unknown to Boulton just a few days later.
Ms Goddard said that officers also found a nine-month old baby crawling around the house “untouched and unharmed but clearly distressed”.
Jurors heard that after the attack Boulton had spent the night on the run.
Ms Goddard said at one stage he broke into an empty cottage at Hubbards Hills, on the outskirts of Louth, where he stole some alcohol, clothing and food and left a note saying “I, Daniel Boulton, take full responsibility”.
The next day he assaulted off-duty police officer PC Stephen Dennis who was walking his dog near Hubbards Hills and tried to detain Boulton.
Boulton was later cornered in a barn and tasered after trying to get some of the armed officers to shoot him, the court heard.
Ms Goddard told the jury there is “no dispute” Boulton stabbed both victims, but that he claims he was “suffering from a recognised mental condition which substantially impaired his ability to form a rational judgement and exercise self-control”.
Boulton, of Alexandra Road, Skegness, denies murdering Ms Vincent and her son.
The trial continues.