Answer the following question: Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: Who altered Ames' lethal injection? Title: Law Abiding Citizen Movie plot: Clyde Shelton (Gerard Butler), a Philadelphia engineer, witnesses the rape and murder of both his wife and five-year old daughter at the hands of two burglars who break in his house: Clarence J. Darby (Christian Stolte) and accomplice Rupert Ames (Josh Stewart), leaving Shelton emotionally scarred. He is told by career-minded prosecutor Nick Rice (Jamie Foxx) that the case was compromised by a bungled forensic investigation and Shelton's testimony cannot incriminate either man because he blacked out during the incident. Rice, interested in maintaining his 96% conviction rate, makes a secret deal with Darby: in return for pleading guilty to third-degree murder, he will provide testimony that will send Ames to death row for what is, essentially, a robbery charge. Shelton is left feeling betrayed.Ten years later. Ames is executed via lethal injection. Due to an alteration in the chemicals, he dies in agonizing pain. Initial evidence leads to Darby, who is alerted to approaching police by a mysterious caller who tells him where a pistol he can use to his advantage is. The caller tells him if he wants to escape the police, he will come to where he is. At the meeting place, Darby realizes that the caller and his savior is none other then Shelton. Darby tries to shoot him with the pistol, only to be discover it is a trick gun, injecting him with tetrodotoxin, paralyzing him, but leaving him fully conscious. After restraining him and making preparations to ensure his prolonged awareness, Shelton slowly tortures and dismembers Darby, saying the words Darby told him 10 years before: "You can't fight fate." It is later revealed that Darby was found in 25 pieces, and after an investigation, Rice and his team suspect Shelton.The next day, a local SWAT unit bursts into Shelton's house to find him waiting for them, and he doesn't resist arrest. In an interrogation cell at the jail, Rice covertly congratulates him for removing Darby from society, then asks for a confession. By all appearances co-operative, Shelton offers a...
Answer:
Shelton