How the Manhattan Bombings could have been prevented with little intrusion into people’s lives

I value my privacy, and I don’t buy the argument that “it’s ok if you have nothing to hide”. But I am surprised how the alleged Manhattan bomber was not stopped earlier. Hindsight is 20/20, but simple use of analytics (yes, "Big Data", but just metadata) could have prevented this tragedy.

2 critical pieces of information came to light AFTER the bombing:

1.  The police was warned about the suspect TWICE since 2014
• http://www.nytimes.com/2016/09/22/nyregion/new-york-new-jersey-bombing.html?_r=0 
2.  He bought most components he used in his bomb off eBay.
•  http://abcnews.go.com/US/nyc-explosion-buying-bomb-parts-ebay/story?id=42243357

I am quite sure that the authorities have a clear idea of the raw materials that can be used to make bombs. Sure most of these are at least dual-use.

Citric acid is a well known preservative, but if you are not engaging in large scale food production, then it is unlikely that you’d need industrial volumes of citric acid.

Similarly, ball bearings are very commonly used in all sorts of equipment; if you are sitting on a swivel chair while reading this post, it is likely that you have ball bearings right under you. Again, if you are not engaged in manufacturing or repair of equipment with moveable parts, then you are unlikely to need ball bearings on a large scale.

Now when you combine citric acid, ball bearings and other ingredients, you end up with a potential recipe for a bomb.

What I am saying is:

1. The combination of individual dual-use items purchased over time should be enough to trigger an alarm, and this could be done by eBay itself.
2. Adding context is important (and this is where many “Data Science” endeavours fail since they do not incorporate “domain knowledge”), since these items are dual use, and there are more avenues for purchase on top of eBay. Hence, someone not engaged in food preservation ordering large amounts of citric acid should trigger a flag. Then a deeper search can be conducted.
3. A deeper search can be conducted once flags are raised, either by the combination of purchases, or by contextually strange purchases. What is key here is that only ‘metadata’ is required to paint the picture.

For example, the credit cards/bank cards/account details attached to the online ordering platforms can be tracked to the individual and transactions on all his/her cards/accounts checked for confirmation of the suspicious patterns. 

Furthermore, basic Call Data Records of phones associated with the individual can be accessed to show possible alternate locations such that more than just the residential address is included in the deeper search. And in case deeper analysis still is required, simple SNA run on the individual and his/her associates and their locations also included in the deeper dive.

All this is quite easily done if you have access to the metadata.

But you don’t need the metadata of everyone to be pulled out and analysed, only those flagged by their purchases, online behaviour, or as in this case, by people who suspected them.

And that is the most glaring part. You can argue that not all bomb recipes are known, and some purchases of dual use items might escape notice, and even combination of these or out of context purchases (after all, a farmer might decide to use fertiliser for bomb making, hence context is not exculpatory by itself). But once an individual is flagged, it would be a good idea to monitor such simple clues to what he/she might be up to, and avoid tragedies.