There was a war between the NF and Eme years before Rudy Cadena's death. Cadena was really trying to bring all NF and Eme members together; however, there were still green lights to kill NF members in other prisons at the time. The war really stemmed from The original NF members being former Eme members and many cholos from Southern California and East La Varrios whom refused to run with Eme and instead formed and ran NF with Farmeros seen as lower class.
Back to the question though, yes Rudy was stabbed and killed by NF members because NF members were under suspicion that Cadena and Eme was setting up the lesser members of NF.
My bad, I read a lot of books and got older homies who gamed me up.