Kylee Butterick said her family was “just so sad” as they tried to process her son William Holdback’s violent death last Wednesday morning.

“We’re just so devastated that we’ve lost the most beautiful boy, William,” she told reporters outside Adelaide Magistrates Court on Monday.

A crowd of Holdback’s friends and family filled the courtroom as his alleged killer, Liam Slann, appeared via video link.

Slann, 26, is alleged to have murdered the 21-year-old during a clandestine late-night rendezvous in an industrial cul-de-sac in Welland in the city’s west.

Police allege Holdback fled on foot from two men in a BMW after an exchange became heated.

One of the men was captured on CCTV footage chasing Holdback down as he cried for help in vain.

His screams were heard by a group of nearby musicians, who found the young man with critical injuries from which he could not recover.

Slann was arrested late on Saturday night and charged with murder.

Police seized the BMW they believe was used in the killing but are yet to lay charges against the owner.

“That person’s role before, during and after the murder is now the subject of an intense and ongoing investigation by detectives,” police said on Sunday.

Slann’s lawyer did not apply for bail as he faced court for the first time on Monday.

The Elizabeth East man will face court again in October after prosecutors successfully sought a seven-month adjournment to analyse DNA evidence, the CCTV footage and conclude their investigations into the presumptive co-accused.

Outside court, Butterick thanked police for their quick response.

“We have been advised not to comment because the other perpetrator is still not caught,” she said.

“When that happens we won’t be happy, but we’ll be a little bit more satisfied.”

– AAP