▁Although ▁one ▁contemporary ▁newspaper ▁report ▁estimated ▁that ▁up ▁to ▁seven ▁people ▁died ▁in ▁the ▁attack , ▁four ▁did ▁definitely ▁die : ▁a ▁Jersey ▁City ▁polic eman , ▁a ▁Le high ▁Valley ▁Rail road ▁chief ▁of ▁police , ▁a ▁ten - week - old ▁infant , ▁and ▁the ▁bar ge ▁captain . ▁ ▁Investig ation ▁ ▁In ▁the ▁immediate ▁after math ▁of ▁the ▁explos ion , ▁two ▁watch men ▁who ▁had ▁lit ▁sm ud ge ▁p ots ▁to ▁keep ▁away ▁mos qu ito es ▁were ▁question ed ▁by ▁police ▁but ▁the ▁police ▁soon ▁determined ▁that ▁the ▁sm ud ge ▁p ots ▁had ▁not ▁caused ▁the ▁fire ▁and ▁that ▁the ▁bl ast ▁had ▁likely ▁been ▁an ▁accident . ▁ ▁So on ▁after ▁the ▁explos ion , ▁susp icion ▁fell ▁upon ▁Michael ▁Krist off , ▁a ▁Slov ak ▁imm igr ant . ▁Krist off ▁would ▁later ▁serve ▁in ▁the ▁United ▁States ▁Army ▁in ▁World ▁War ▁I , ▁but ▁admitted ▁to ▁working ▁for ▁German ▁agents ▁( transport ing ▁suit cases ) ▁in ▁ 1 9 1 5 ▁and ▁ 1 9 1 6 ▁while ▁the ▁US ▁was ▁still ▁neutral . ▁According ▁to ▁Krist off , ▁two ▁of ▁the ▁gu ards ▁at ▁Black ▁Tom ▁were ▁German ▁agents . ▁It ▁is ▁likely ▁that ▁the ▁bomb ing ▁involved ▁some ▁of ▁the ▁techniques ▁developed ▁by ▁German ▁agents ▁working ▁for ▁German ▁amb assador ▁Count ▁Johann ▁Heinrich ▁von ▁Bern stor ff ▁and ▁German ▁Naval ▁Int elligence ▁officer ▁Franz ▁von ▁R int elen , ▁using ▁the ▁cig ar ▁bomb s ▁developed ▁by ▁Dr .