He also emailed a long manifesto to his family and to his therapist.
Then last Friday in Isla Vista, California, he went on a shooting rampage before ending his own life.
On any other day that story might get written off as the tale of one sick psycho in an otherwise sensible world, but thanks to Twitter it became a catalyst for something much bigger.
The fact that Rodger actually acted out his threats captured the attention of women who began to tweet about their own experiences of being threatened by men.
They were joined by more women, and then more. The tweets boomed into a collective protest directed at the entire spectrum of sexual abuse and harassment, from rape to leering co-workers.
The tweets were united under the hashtag #YesAllWomen. A hashtag works like a link. You can put a hash in front of any word in your tweet and it will create a link to every other tweet that happens to be using that same hashtag.
Most hashtags wither and die in obscurity, but some gather momentum and "trend".
For nearly a whole week, the hashtag #YesAllWomen sat at the top of the list of trending topics on Twitter.
At first I didn't know what to make of it. "Yes all women?" What does that even mean?
The best explanation comes straight from one of the tweets, which reads: "Because every single woman I know has a story about a man feeling entitled access to her body. Every. Single. One. #YesAllWomen."
This is where it gets real for us ordinary guys who assume we're not part of the problem. The story of Elliot Rodger is actually a red herring. The #YesAllWomen tweets were railing in general against men's sense of sexual entitlement.
Every woman has a story about an icky man. It boils all the way down to the subtle ways men treat women, perhaps without even realising it. It's the difference between wanted and unwanted attention.
Not all men are to blame, but yes, all women have to negotiate their way through a male-oriented world that can at times make them feel vulnerable or intimidated or just plain disgusted.
I'm happy to go for a run in the evening but my wife is not. Men twice her age have leaned over her with nudges and winks in a supposedly professional workplace.
Are they trying to live vicariously through their inappropriate compliments? The line was way back there, buddy.
I'm ill-equipped to comment with much insight on this topic. It seems I've been strolling obliviously through my male universe without ever pausing to question things from a female perspective.
For that reason alone #YesAllWomen has been a positive moment in the fickle history of internet fads.
It has shone a spotlight on to something that deserves to be discussed in the open.
I never realised there were so many creeps among us.
Not all men, but yes, all women probably know what I'm talking about. I'm sure we can do better.
A little bit of respect goes a long way.
Marcel Currin is a Tauranga writer and poet
