This worked pretty well for me. I just had to change one line in order for it to run.
for subtree in sentt.subtrees(filter=lambda t: t.node == 'PERSON'):
needs to be
for subtree in sentt.subtrees(filter=lambda t: t.label() == 'PERSON'):
There were imperfections in the output (for example it identified "Money Laundering" as a person), but with my data a name database may not be dependable.