You are referring to 2-factor authentication for gmail and google accounts. That is not the same as using the google 2fa open source code that does not link back to google at all. The exchanges are using the later.
Oh anything can be traced if you have enough manpower. Looks like Bittrex gave the users all the information about who logged into their accounts. If those users want to find out who stole their stuff they should file police reports and get the process started.
The problem is this isn't women at the shelter because their husbands smacked them around. It's because they were sleeping around with a trojan horse. Their machines were hacked, not bittrex, the burden is on them, bittrex is just one piece of information that they can obtain, contacting the FBI would do nothing for these people as the FBI wouldn't even bother doing anything with this.
So my frighten stalker returns,
It funny you claim to know their was no phone # attached to that specific 2fa.
Either Bittrex or Google has a Phone # stored for that 2fa account.
https://www.bittrex.com/Manage#section2FaBittrex encourages the use of two-factor authentication
Two-factor authentication (2fa) greatly increases security by requiring both your password and another form of authentication. Bittrex implements 2fa utilizing Google Authenticator.
To enable this feature simply download Google Authenticator on your mobile device and scan the QRCode.
Once you have linked the Authenticator with Bittrex, enter the 6 digit code provided.
Please back up your secret key. Reseting your two - factor authentication requires opening a support ticket and may take up to 48 hours to address.
You claim to know alot, but give no details where you receive that info or even provide a reference.
Mostly you just make up stories with the pretense of knowledge, when it is apparent you are lacking in that area.
Bittrex has not given all of the log info to the users, they cited privacy laws, can you not even read the previous posts before you contradict just to be contradictory.
That the real issue, Bittrex is hiding data, that legally they could only give to the Legal Authority.
Are you and the others really so stupid, that you believe a hacker had total access to their PCs.
But did not go after their
Bank Accounts or
Credit Cards and only focuses on 1 crypto exchange and ignore every other exchange.
Are you really that Stupid?
Just Asking cause you seem to be that stupid. 
FYI:
The committed crime crossed State Lines, and would be in the the FBI jurisdiction not local Police.
Whether the FBI does anything is up to them, funny that Bittrex is afraid to report it to them.
https://www.fbi.gov/about-us/investigate/what_we_investigateSpies. Terrorists. Hackers. Pedophiles. Mobsters. Gang leaders and serial killers. We investigate them all, and many more besides.
https://www.fbi.gov/about-us/investigate/cyber/computer-intrusions 
You're not understanding how google authenticator works on most of these sites, which is ok, because you probably haven't done web development or ever tried to implement a 2factor solution. Most sites that are not associated with google use their open source version of the authenticator. You can even run the application from a windows box with no phone number associated and no google accounts. If you don't believe me go try and enable 2fa and do some packet sniffing while its happening, you won't see any network traffic, thus no way to get your phone #etc.
http://stackoverflow.com/questions/5087005/google-authenticator-available-as-a-public-serviceYah I read the thread they were given their logon history which shows some random ips logging into their account. That should be enough to get an investigation started, they can contact the FBI like you said.
You have no proof they didn't steal anything else, do you know how many had funds somewhere else? If any? Hackers tend to move quick when they get a compromised machine and since all of these hacked people obviously are into crypto the hacker probably tricked them into clicking something crypto related, maybe they even knew these people traded at Bittrex from whatever forum they were posting in.
