Sentence:  On one of his 1921 ventures he was actually come upon by a Detective Sergeant John J. Ryan down on his <WSD>knees</WSD> with a tool embedded in a labour office safe in the Postal Telegraph Building ; the jury wanted better evidence than that and he was acquitted , at a cost of $ 30000 in bribes , it was estimated . 
Meaning of the word marked with <WSD> tags:  hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella