As of February 28th 629,375 warrants were outstanding at .15 and expiring on September 15, 2017. According to the monthly CSE reports, the warrants/options that were exercised in Mar/Apr/May were not the .15 ones.
They seem to belong to Keith Spinelli, who was holding a bunch of shares in early 2016. I'm not too sure if he's helping to crater the current price, but he's probably the safest bet.
And apologies to Keith if that corporate link is not him... just what google gave me and it seems to fit.