Mobile phone footage apparently showing the inside of a Scottish courtroom during a case has been posted on the video-sharing website YouTube.
It is said to show three youths appearing at the High Court in Glasgow earlier this year, where they later admitted beating a young man to death.
The clip called "the troops in the high court" lasts less than three minutes.
A spokesman for the Crown Office said Strathclyde Police had been instructed to investigate.
Maria Smith, whose 21-year-old son William was killed by four men who boasted about the killing on YouTube, said she was aware of postings on the site.
She said she believed the footage was of an early hearing of the case.
"It was sickening," she said. "We've never had a chance to move on and it will take us a hell of a long time to move on. I feel sick that they're able to go into a High Court with a phone. It's unbelievable, absolutely unbelievable."
A police spokeswoman said: "Strathclyde Police can confirm that correspondence has been received from the Crown Office and we are investigating."
If the footage is genuine, it would be a breach of the law. Whoever shot the film faces a potential contempt of court charge.
Recording of any kind is banned in Scottish courts, except under special circumstances.
A spokeswoman for the Scottish Courts Service said it would be launching an investigation.
A YouTube spokesman said the video sharing website had clear policies that prohibited inappropriate content on the site.
"If the police ask us for information, we will co-operate, so long as they follow the correct legal process that the government introduced."