MacBook Pro locked using Find My Mac I bought a MacBook pro from a guy who I met in online . Everything looked perfect at the time of purchase. 
But later, I  connected it to the Internet and all of sudden it got a locked screen over there. When I tried contacting the seller he seems off and gave no response. I feel suspicious now and planning to take it Apple store today for further actions. In the worst case if it’s stolen, they may help to find the owner. I am also leaving the country in one day.

Any other suggestions welcome to help me either unlock it or reach the owner.  

Edit:  It seems like a stolen Mac only . My bad purchasing it. Is there any other way I could find owner myself so at least return to them since I have less than 24 hours for my travel?
Unfortunately, it seems that you purchased a system that had Find My Mac enabled. This leaves you at the mercy of the iCloud account owner to not lock the system. I doubt there is anything Apple can/will do to help you unlock it. They may be able to help locate the account owner.

Advice for next time: Always check System Preferences to ensure that Find My Mac is disabled before handing over any money. To be completely safe, boot to Recovery Mode by pressing Cmd+r at the startup chime. Enter Disk Utility and format the Macintosh HD. Following that, use internet recovery to reinstall macOS.

That might seem like a lot of work, but it ensures that there is no malware on the system left behind by earlier users of the system, whether intentionally or otherwise.