Let
$R$ be an
$n!$ -torsion free semiprime ring with involution
$*$ and with extended centroid
$C$ , where
$n\,>\,1$ is a positive integer. We characterize
$a\,\in \,K$ , the Lie algebra of skew elements in
$R$ , satisfying
${{(\text{a}{{\text{d}}_{a}})}^{n}}\,=\,0$ on
$K$ . This generalizes both Martindale and Miers’ theorem and the theorem of Brox et al. In order to prove it we first prove that if
$a,\,b\,\in \,R$ satisfy
${{(\text{a}{{\text{d}}_{a}})}^{n}}\,=\,\text{a}{{\text{d}}_{b}}$ on
$R$ , where either
$n$ is even or
$b\,=\,0$ , then
${{(a\,-\,\lambda )}^{[(n+1)/2]}}\,=\,0$ for some
$\lambda \,\in \,C$ .