A picture mocking the death of Emiliano Sala is circulating ahead Swansea v Cardiff on Sunday.
Swansea City say an image that's being circulated on social media mocking the death of Cardiff City's Emiliano Sala is 'disgraceful' and 'shameful'.
It comes ahead of the big south Wales derby game tomorrow.
The two clubs haven't faced each other in more than 5 years.
Sala had just signed for Cardiff City when he was killed after a private plane taking him from France to the UK crashed in the English Channel north of Guernsey on January 21.
The image of is of a boarding pass with Sala's name on, the flight number listed as "D3ad", and the words "Swansea City airlines".
As they investigate, South Wales Police have reminded people not to share the image as they may be committing an offence.
Swansea City have released a statement on their website.
"Swansea City is aware of the disgraceful image currently circulating on social media ahead of Sunday’s South Wales derby in relation to the sad death of Cardiff City striker Emiliano Sala.
We are working closely with South Wales Police who will be conducting an investigation to identify the initial source.
The image is shameful and does not represent this football club or our supporters in any way.
We have a zero-tolerance policy towards any discriminatory, unacceptable or anti-social behaviour, and this will be enforced rigorously before, during and after Sunday’s South Wales derby.
Any supporters displaying this type of material or behaving in an unacceptable manner will face criminal proceedings.
The club will be strongly supporting South Wales Police in any public order or hate crime prosecutions surrounding these images and any related incidents during Sunday’s fixture at the Liberty Stadium."
South Wales Police say they'll be working with both Swansea and Cardiff City football clubs to try and identify the source of the image.
Anyone with information should contact 101 or Crimestoppers on 0800 555 111 quoting occurrence 1900395865