Deividas Skebas killed nine-year-old Lilia Valutyte by stabbing her in the heart as she played with a hula hoop in the street, a jury has decided.

Skebas, 23, was deemed unfit to plead or face trial due to his mental health, and on Tuesday after a two-day trial of the facts at Lincoln crown court he was found to have committed the killing.

The jury were shown CCTV footage of the moment Lilia received a single stab wound to the chest as she was playing in the street in Boston, Lincolnshire, on the afternoon of 28 July last year.

After about 15 minutes of deliberations, the jury unanimously decided Skebas physically committed the killing of Lilia.

They could not deliver a verdict of guilty or not guilty of murder as a trial of the facts is not to decide whether someone intended to commit an act but to determine whether they physically did it.

While a defendant cannot be criminally convicted, the burden of proof for a jury remains beyond all reasonable doubt.

Skebas could stand in a conventional trial in future if his mental health improves.

Mrs Justice McGowan detained Skebas in a secure hospital for an indefinite period – the only sentence the court could pass – hours after jurors returned their determination after about 15 minutes of deliberation.

The prosecutor Christopher Donnellan KC read the court a transcript of Skebas’s interview with police after his arrest, in which he said: “I grabbed the knife and I stabbed her.”

CCTV footage played in court showed a man alleged to be Skebas pacing around Boston town centre on the evening of 28 July last year, having been seen buying a paring knife in the town’s Wilko store two days earlier.

At about 6.15pm, the man was seen running towards Lilia, who was playing with a hula hoop outside a shop where her mother worked. He stabbed her once and ran away. Lilia died at 7.11pm, the blade having pierced her heart.

The knife was found “tucked behind a radiator” when police searched Skebas’s property in Boston two days later. They also found a blood-stained grey Calvin Klein T-shirt, and DNA from the blood matched that of Lilia.