Manzarek, who co-founded the band with Jim Morrison in 1965, lost his battle with bile duct cancer in May (13) and his passing prompted Krieger and drummer John Densmore to end a longrunning feud and discuss plans for a tribute concert.
However, the guitarist admits he is still stuck in the grieving process.
Krieger tells Billboard.com, "It's taking a while to get over it. I knew him for so long. I still think about him every day, and I'm constantly doing interviews and stuff about him."
Krieger and Densmore fell out during a legal battle over the use of the band's name a decade ago - the drummer opposed Krieger and Manzarek's plans to tour as The Doors of the 21st Century and forced his former bandmates to change the title.