Query Blockchain: Reference previous transaction in "txin"
txin.prev_out contains the txid in internal byte order. This is the opposite of tx.hash

You need to reverse the bytes. Here's a short python program that will do that:

import binascii
hash = '32d7724fb0d244f50281a500f505818bb655bc029158fd59d477f4445a6ed64a'
def reverse_hash(hash):
    hash = binascii.unhexlify(hash)
    hash = hash[::-1]
    return binascii.hexlify(hash)

print reverse_hash(hash)