lol. Well done. You definitely win the prize for most entertaining run.
And you poisoned Lettiere. Thank you!
The guard who spotted you is tricky. He turns and looks down the alley periodically, but he's hard to spot from the alley because there's a plant in the way.
I either killed Lettiere while he was walking to the toilet and dumped him in the alley bin, or waited for him to finish throwing up and lured him into the cafe basement.