The strychnine had been found in a drawer in the prisoner's room. 
( ( The strychnine ) ( ( had ( been ( found ( in ( ( a drawer ) ( in ( ( the ( prisoner 's ) ) room ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN strychnine)) (VP (VBD had) (VP (VBN been) (VP (VBN found) (PP (IN in) (NP (NP (DT a) (NN drawer)) (PP (IN in) (NP (NP (DT the) (NN prisoner) (POS 's)) (NN room)))))))) (. .)))
They found the strychnine under the prisoner's bed. 
( They ( ( ( found ( the strychnine ) ) ( under ( ( the ( prisoner 's ) ) bed ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD found) (NP (DT the) (NN strychnine)) (PP (IN under) (NP (NP (DT the) (NN prisoner) (POS 's)) (NN bed)))) (. .)))