In the country of Sercia, Wild Dog and his mercenary army were hired by the disposed Imperial dictator Sherudo Garo to help him stage a coup against the democratically elected government. In response to the uprising in Sercia, the Vital Situation, Swift Elimination (V.S.S.E.) organization sent Richard Miller to stop Wild Dog and Garo. Miller managed to locate and kill Garo. Wild Dog took the president's daughter hostage and started to make his way to the roof of the castle in order to reach a helicopter and make his escape. Wild Dog began setting off explosive charges in the area in an attempt to kill Agent Miller, but Miller managed to catch up with Wild Dog and his remaining soldiers. After a long battle, Wild Dog was defeated and accidentally dropped his radio detonator which activated as it landed on the ground. Wild Dog was engulfed in flames and caught in a massive explosion that seemed to kill him.
Time Crisis: Project Titan
Wild Dog had survived the explosion at the end of Time Crisis and returned with a machine gun grafted onto his left shoulder in TC: Project Titan. Richard Miller also returned to stop the assassin Richardo Blanco, a member of The Wild Dogs. Richardo and Miller engaged in an intense firefight at Blanco's mansion. Miller was defeated and attempted to make his escape by helicopter, but Wild Dog appeared and gunned him down. Miller failed to stop the mercenary only to discover that Wild Dog was creating an army of robot soldiers deemed "Project Titan". Wild Dog and Miller once again began exchanging fire and once again Wild Dog was defeated. In desperation, he sent his army to kill Miller as he tried to make his escape via helicopter. However, Miller managed to shoot down the helicopter, causing it to crash and destroy the robotic army. Wild Dog was assumed to be killed.
Time Crisis II
During the introduction sequence of Time Crisis II, Cristy Ryan reported to V.S.S.E. agents Keith Martin and Robert Baxter that Wild Dog was still alive and working for corporate CEO, Ernesto Diaz. When Baxter and Martin reached Neodyne Industries satellite launch site, Wild Dog and a group of soldiers confronted them. Diaz later joined in the battle with a rocket launcher but this did not stop the two agents from defeating Wild Dog. As he laid dying, Wild Dog exclaimed, "V.S.S.E.! You fools!" The merc pulled out a radio detonator and activated an explosive device he had on him; they thought he was dead.
Time Crisis 3
Despite being near death three times before, Wild Dog returned to kill V.S.S.E. agents Alan Dunaway and Wesley Lambert. When the agents encountered Wild Dog they are shocked by his appearance and ask, "Don't you ever Die?" Partnered with Wild Dog was Wild Fang; a second mercenary who dressed very similarly to Wild Dog who had accepted him as his apprentice. Fang is much younger than Wild Dog and has the ability to kick large objects such as bulldozers and shipping containers with deadly speed. While he no longer uses martial arts, Wild Dog had installed a multi-weapon gun onto his left arm; it functioned as a flame-thrower, a rocket launcher, and a Gatling gun. Wild Fang fell to the floor one he was defeated but Wild Dog managed to detonate himself again with his radio detonator... By now you should know that he isn't dead.
Time Crisis 4
Wild Dog returns in Time Crisis 4 sporting two new modifications to his gun-arm; a grappling hook and tractor beam. He used his grappling hook to pull down a helicopter carrying the V.S.S.E. agents Giorgio Bruno and Evan Bernard at the Colorado Air Force Base. Afterwards, he retreated into a hanger where he had set up several traps for the two agents. Wild Dog used his tractor beam to throw objects at the two agents during their inevitable firefight. Wild Dog was once again defeated by V.S.S.E. agents. The battle had damaged his tractor beam which attracted several objects that buried him in debris. As Bruno and Bernard approached the pile, Wild Dog pulled his detonator out of the rubble and blew himself up again.
Until the next Time Crisis game is released, we won't know Wild Dog's fate. But its a pretty safe bet to assume he is alive.