We study the capitulation of 2-ideal classes of an infinite family of imaginary biquadratic number fields consisting of fields $\mathbb {k} =\mathbb {Q}(\sqrt {pq_{1}q_{2}}, i)$ , where $i=\sqrt {-1}$ and q 1≡q 2≡−p≡−1 (mod 4) are different primes. For each of the three quadratic extensions $\mathbb {K}/\mathbb {k}$ inside the absolute genus field 𝕜 (∗) of 𝕜, we compute the capitulation kernel of $\mathbb {K}/\mathbb {k}$ . Then we deduce that each strongly ambiguous class of $\mathbb {k}/\mathbb {Q}(i)$ capitulates already in 𝕜 (∗).