Shog9 already took care of this particular user, but if I could, I'd like to make a suggestion for future flags of this type.
It really does help us if you can present as much evidence as you can in your custom flag. Even stating what you did above, that a series of votes came in within minutes on a certain date, can save us a lot of time in processing these flags. If a user is just flagged with nothing more than "suspicious voting here" or the like, we have to go digging around ourselves in a few places to see if anything jumps out at us. Different moderators will have different ways of doing this, and we may miss the warning signs that you've picked up on if you don't spell them out for us.
Also, the scale of the voting anomalies matters, because a handful of votes in a string here or there can happen due to normal usage and may not point to a larger problem. We really want to avoid any false positives here, because of the serious consequences, so we tend to be a little more cautious when acting on small-scale voting patterns. I've declined a few flags myself for this reason, where I couldn't see enough to make a case for acting on a user. Again, there might be something I've missed, so please do lay out your case in the custom flag.
Manipulation of the voting system is a serious issue, but it can be hard to suss out and the penalties we impose can be harsh, so every bit of information we have to work with is appreciated. Now that I've transitioned over to being a moderator, I've looked back at a few of the flags I previously cast on what I thought were obvious voting patterns but were declined. I realize that I hadn't made a good enough case for what I saw there, and should have been more detailed in those instances.