On iterated powers of positive definite functions

We prove that if $\rho$ is an adapted positive definite function in the Fourier--Stieltjes algebra $B(G)$ of a locally compact group $G$ with $\|\rho\|_{B(G)}=1$, then the iterated powers $(\rho^n)$ converge to zero in the weak* topology $\sigma(B(G) , C^*(G))$. Moreover, if $\rho$ is irreducible, we prove that $(\rho^n)$ as a sequence of u.c.p. maps on the group $C^*$-algebra converges to zero in the strong operator topology.