An Arizona woman is behind bars after allegedly attempting to slowly kill her husband by putting bleach in his morning coffee for months.

Melody Johnson of Tucson was indicted by a grand jury on charges of first-degree attempted murder, attempting to commit aggravated assault and poisoning food or drink, CNN reported. She was arrested on July 18, NBC News reported.

Court documents obtained by KVOA-TV in Tucson say that the husband — who was not named in initial reports but is identified by CNN as Roby Johnson — began to suspect his wife of poisoning him at the end of March. Roby is in the U.S. Air Force and was stationed in Germany at the time. The couple were going through a divorce but were still living together in the country with their son.

In March, Roby says, he noticed his coffee had started having a “bad” taste, according to the documents. Several weeks later, he purchased pool chemical test strips. He tested the water in his faucet, which came back normal. But when he tested the water in his coffeepot, it showed “high levels of chlorine,” the documents say.

In May, Roby set up a camera in the home, which captured Melody “pouring something into his coffee pot,” according to the complaint. Roby stopped drinking the coffee at that point but said he pretended to continue to drink it until the family returned to the U.S. on June 28 because he didn’t want to file a report in Germany.

On July 5, Roby reportedly caught Melody on camera “walk to his coffee maker and pour something into his water reservoir” while the family was temporarily stationed at a hotel on Davis-Monthan Air Force Base in Tucson. Roby showed the video to police, but officers told him that whatever Melody poured into the machine’s reservoir wasn’t apparent and that his report was “taken with no follow up,” according to the complaint.

When the family moved to permanent housing on July 7, Roby set up more cameras that looked like fire alarms that attached to the ceiling, according to court documents. One was placed in the laundry room, where bleach was kept, another was placed over the coffee machine and a third was placed to show the space between the two areas, the documents said.

With the new setup, Roby was able to collect multiple videos that show Melody “take bleach, pour it into a container and then walk over and pour it into the coffee maker,” the documents say.

After Melody Johnson was arrested, a search warrant was served on the residence, where police found a liquid in the coffee maker “that smelled like bleach” as well as a container beneath her bathroom sink that also smelled like bleach.

Investigators say Roby Johnson “believes she was trying to kill him to collect death benefits,” according to the court documents.

Melody Johnson is being held at the Pima County Jail until her next court appearance, scheduled for Sept. 6, CNN reported.

The complaint also said that a high bond is recommended because Melody Johnson recently bought a house in the Philippines near family and so is considered a flight risk.