Nadeem-Shravan really are murderer ?

was they really killed gulshan kumar ? or was he got targetted by some compitator as nadeem shravan were ruling bollywood scene in 90's and in 97 when all the gulshan kumar thing happened they came back with yeh dil aasiqana , kasoor , dil hai tumhara , dharkan , haan maine bhi pyar kiya hai , dosti , tumsa nahi dekha , raaz, tumse acha kaun hai all these albums are now classics ...Shravan parted with nadeem as sharavan also supported allegation against nadeem saifi

[YOUTUBE]https://www.youtube.com/watch?v=lrB1jc_yReI&spfreload=10[/YOUTUBE]