Mobile footage will form a crucial part of the investigation into the alleged murder of a 24-year-old Queensland man after he was fatally stabbed at a Brisbane train station yesterday morning.

The footage captured Lauie Tagaloa's final moments as a brawl between two groups of men allegedly erupted in Fortitude Valley's Valley Metro shopping complex and train station around 4am, July 11.

Seyram Kwami Djentuh, 20, has been charged with Tagaloa's alleged murder.

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The video footage is said to show the alleged brawl, depicting men lunging and shouting at each other during a confrontation in the shopping centre.

Tagaloa is then allegedly stabbed in the neck and left dying on the floor while his suspected attackers flee the scene.

Three men were later located by police with the alleged murder weapon at one of the train station's platforms.

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Police confirmed both CCTV and the mobile phone footage will play a crucial role in the investigation.

The shopping centre's extensive CCTV network was used to locate the alleged killer and witnesses.

"Police were watching the BCC CCTV when they observed a disturbance taking place in the public thorough fare of the fortitude valley railway station," regional duty officer Sean Cryer said.

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"On close examination they saw a male person lying on the ground, the persons nearby had blood on them- we immediately dispatched the QAS and uniform crews to the railway station."

"A search was conducted for those persons, they were located on platform 4, a weapon was located."

A lawyer for Djentuh did not give a comment on behalf of his client.

Djentuh has been remanded in custody and will appear in court August 8.