I do not have information about the LA Police nor the DoD. You can see live data at https://blockchain.info/
You could get some interesting plots out of it, say the number of transactions per week day, the volume etc. They have all kinds of charts here https://blockchain.info/stats, so you can see the data over time.
If you want to get in the tech have a lookat https://code.google.com/p/bitcoinj/ (java) or https://pypi.python.org/pypi/python-bitcoinlib/0.2 (python). Also, read the original paper - its more clear than reading code
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On YouTube are some videos as well, online cryptocurrency course If im not mistaking
Try to make a fork or something small