Doctor Lesko

 created the Fire Ants that carried off or killed almost everyone in Grayditch. He was experimenting to return giant ants to their normal size through genetical manipulation and accidentally created the fire ants. Despite the death and destruction his experiments caused, Lesko remains indifferent to the lives lost, stating that the completed goal of his project will save countless more.

Lesko has a shack by the diner which requires Average Lock-picking Skill, or the key to enter. He can be found deep underground in the Marigold Station. He is involved in the quest Those! which can be obtained from him or alternativley you will be approached by Bryan Wilks who will trigger this quest, Doctor Lesko's quest offers either Ant Sight or Ant Might as a reward, the player can choose between the two. Lesko can sometimes be killed by fire ants if you leave both doors to his office open, close them after speaking to him to ensure he is not killed before you have completed his quest.

Note: If you don't select the extra payment option during the quest, you cannot obtain Lesko's Lab Coat. Killing him after completing the quest will net just a loss of Karma. The clothing he has on him is just a normal Lab Technician Outfit.

Appearances
 only appears in Fallout 3.

Bugs
It has been reported that Lesko has been found dead by some players before you start the quest, so it is suggested that one does not wait too long to complete the "Those!" quest until the exact parameters of this bug has been discovered and hopefully repaired.

This bug can be fixed in the PC version by clicking Lesko's corpse in console mode and typing "resurrect". If he cannot be found, his prid is 000393EB.

You should get the Ant Might / Ant Sight perk immediately when offered by Doctor Lesko. If you delay getting it until Doctor Lesko is back in his shack, you might not get the dialogue option to get the Ant Might / Ant Sight perk. Also, adding the perks Ant Might (000C1A6B) or Ant Sight (000C1A6C) through the console, the radiation resist may not be added to your character.

Behind The Scenes
Doctor Lesko is likely named for Matthew Lesko, an author who compiles books on how to take advantage of government programs. Matthew Lesko enjoys something of a local cult celebrity status in the DC area, due to his wacky television commercials and question-mark-covered vehicles and clothing. Matthew Lesko's website is http://www.leskobooks.com/

Doc Lesko's voice also seems to share an unmistakable similarity to that of resident "Simpsons" 'Mad' Professor, Professor Frink, and to Professor Hubert J. Farmsworth from "Futurama". This may a homage to either or both characters.

Related quests

 * Those!