From an article related to the case [1]:
> charged with criminal cyberstalking with the intent to kill or cause bodily harm and faces a maximum sentence of 10 years in prison if convicted,
What is even more sad:
> More than 40 Twitter users sent similar strobes to Mr. Eichenwald after they realized they could trigger seizures, he tweeted Friday.
The agent went through these steps to identify the suspect:
- Asked Twitter about account information. (w/ search warrant)
- Got phone number
- Phone number was Tracfone prepaid but asked AT&T for information about phone number. AT&T could map [phone number] -> [specific iPhone model] ("DPD sent a request to AT&T")
- Asked apple about iCloud account related to [phone number] (w/ search warrant)
- Find selfie of accused with his DL in hand in iCloud pictures, and also a screenshot of the seizure-triggering GIF, and many other incriminating/stalking behavior items.
[1] http://www.washingtontimes.com/news/2017/mar/18/twitter-user...
EDIT: Added (w/ warrant search) to clarify what "Asked" meant in my summary.