A “ lone wolf” can have all the attributes you mentioned. All he/she did was act alone in the completion of their mission. That is why it is so hard to predetermine a perp if the act is carried out by one person alone. I would imagine most professional hit men fit into this category.
I had just finished reading the Time magazine article on introverts (shy people) and was thinking ‘loner’ - not ‘lone wolf’. You’re right - big difference. I wish my comment had been made at 2 am so I could claim sleep deprivation... but nope - that wasn’t the case. Thanks for the correction. :)