Police in California have appealed to the public for help in tracking down a key suspect in a fatal shooting at a Wiz Khalifa and Young Jeezy concert last year (14).

Record label boss Eric Johnson, 38, was shot backstage at the hip-hop stars' joint Under the Influence of Music show in Mountain View in August (14) and he subsequently died in hospital from his injuries.

Cops have yet to identify the shooter and have now released two sketches of the man they believe may have been involved.

Investigators were unable to provide a detailed description of the suspect, so they have shared one artist's impression showing the male with hair, and one without.

Young Jeezy was arrested by police investigating the murder last summer, when an assault rifle was discovered on his tour bus. His gun possession charge was dismissed in December (14) after his security chief proved the weapons, which had been purchased legally, belonged to him and not the rapper.

Jeezy was not a suspect in the murder case.