A Missouri man pleaded guilty on Monday to making bogus telephone reports in October that water supplies would be contaminated in four cities in Missouri and Kansas.

Manuel Garcia, 70, admitted during the hearing that he called police and federal officials claiming that an unknown substance would pollute water in Kansas City and St. Louis, as well as Wichita and Topeka, Kansas, according to a United States Department of Justice press release.

According to the US attorney's office in Kansas City, Garcia alleged that four men in uniforms of a plumbing company planned to contaminate the water supplies. The contamination would take place within the next 10-15 days in four 55-gallon tanks. And in the good graces of his heart, Garcia said he would help authorities find the men - for a $10,000 reward and a grant of immunity, of course, a federal affidavit in October wrote.

Officials caught on to Garcia's ruse when an FBI agent investigating the calls, Reuters reported, recognized his voice from a previous case in which he made false threats involving explosives outside a federal courthouse in Kansas City, the plea agreement stated. In that case, Garcia was also found guilty and sentenced to 18 months in prison.

Garcia's official punishment will be declared at a later date once the United States Probation Office completes its presentence investigation. Garcia could face up to five years in prison without parole, as well as a fine of up to $250,000, officials said.

He pleaded guilty before US District Judge Dean Whipple to the charge contained in a Nov. 15, 2013, federal indictment.