A Phoenix firefighter was arrested on accusations that he caused more than $25,000 in damage to a townhome after the resident threatened to tell his wife he was having an affair.

Gregory Knauss planned to sabotage the plumbing and HVAC system of the townhome in a retaliation plot, Peoria police said, according to FOX 10 Phoenix.

Detectives said a witness noticed Knauss on the roof of a townhome in Peoria, Arizona, on Jan. 23.

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Gregory Knauss was arrested on accusations that he caused more than $25,000 in damage to a townhome in Peoria, Arizona. (Peoria Police)

Knauss allegedly clogged the townhome's plumbing and roof using spray foam, and vandalized the air conditioning unit. He is also accused of putting holes in the roof.

Detectives said Knauss was involved in a dispute with the townhome's resident over a romantic relationship Knauss allegedly had with the resident's girlfriend. The resident allegedly said he was going to tell Knauss' wife about the affair.

In response, Knauss allegedly texted the resident saying, "I know where you live" and threatened to destroy his life.

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Detectives said Knauss was involved in a dispute with the townhome's resident over a romantic relationship Knauss allegedly had with the resident's girlfriend. (Peoria Police)

On Feb. 27, Knauss was arrested and charged with multiple crimes, including second-degree burglary, criminal damage, harassment and threatening and intimidating.

FOX 10 reported Knauss is a fire engineer with the Phoenix Fire Department.