Floyd Mayweather 'witnessed friend's murder-suicide on FaceTime'

Sources close to undefeated US boxer Floyd Mayweather claim he was on FaceTime with his best friend, rapper Earl Hayes, when Hayes allegedly shot his wife before turning the gun on himself.

According to TMZ Hayes rang Mayweather on Monday angry at claims his wife – backup dancer Stephanie Moseley – was cheating on him.

During their conversation it is alleged that Hayes told the athlete he was going to "kill his wife" to which Mayweather pleaded with him to calm down.

The sources claim Mayweather has not detailed exactly what he saw next – only to say that he "saw and heard everything".

The boxer and Hayes became friends and often partied together after Mayweather signed the rapper to his record label.

Mayweather was named by Forbes magazine as the highest paid athlete of the past year.

Moseley has worked as a backup dancer for a number of artists including Britney Spears and had most recently appeared on the VH1 television show Hit the Floor.