Those deaths were from Tramadol as the vendor(Krypton Kratom) spiked their kratom with O-desmethyltramadol. Link to the study about the toxicology can be found

Those deaths were from Tramadol as the vendor(Krypton Kratom) spiked their kratom with O-desmethyltramadol. Link to the study about the toxicology can be found here: http://jat.oxfordjournals.org/content/35/4/242.long http://jat.oxfordjournals.org/content/35/4/242.long