The United States has, over the years, weakened several important norms and signals that may have discouraged the violent actions of the Saudi government.
Gina Haspel, now in the highest position at the CIA, was involved in the use of "enhanced interrogation" techniques on a suspected terrorist in 2002.
Thanks in part to the work of Hanns Scharff and a slew of studies on interrogation techniques, we know it's best to be genuinely friendly no matter who you're trying to get information out of.