DistributedMember is null in the Interface Authenticator implementation?

DistributedMember is null in the Interface Authenticator implementation.

http://www.gemstone.com/docs/current/product/docs/japi/com/gemstone/gemfire/security/Authenticator.html

Principal authenticate(Properties props, DistributedMember member)

          Verify the credentials provided in the properties for the client/peer as specified in member ID and returns the principal associated with the client/peer

I am trying to implement authentication. I get DistributedMember object as null in locator logs when peer try to join the Distributed System.

Even though I throw AuthenticationFailedException from the authenticate method; my member is still able to join Distribuyed system. Is it somehow related to locator***.dat file?