All the instant body-language experts. Let's convict her because her motions on a blurry security cam definitely rule out "nervously pulling a prank on a stranger" and are only consistent with "highly sophisticated international assassin with no escape plan".
Mentions being recruited months ago, and practice sessions that included injecting the victim. I don't know that a reasonable person would conclude that an injection was a normal thing to do in a prank.
Of course, news is often misreported, so yeah...innocent until proven guilty. But people will speculate, and there are some things that feel fishy.