Appliance delivery man douses 75-year-old woman with chemical, beats her to death with mallet: Police Evelyn Udell, 75, was home alone when a delivery man allegedly attacked her.

A Florida delivery man was dropping off a washer and dryer at a 75-year-old woman's home when he doused her with a chemical and beat her to death, according to police.

Police and fire crews responded to Evelyn Smith Udell's Boca Raton home on Monday morning where they found her unconscious on her laundry room floor with head injuries and severe burns to her body, according to the probable cause affidavit.

Suspect Jorge Luis Dupre Lachazo, 21, and another delivery man, David Gonzalez, installed the new equipment at Udell's house that morning, where she was the only person home, according to the probable cause affidavit.

Gonzalez went outside to return phone calls while Lachazo stayed inside to help answer the customer's questions, according to documents.

Gonzalez told police he heard screams and went back inside to find blood on the floor, authorities said. Gonzalez called 911 and Lachazo allegedly fled in the delivery truck, documents said.

After Lachazo was apprehended, he allegedly told investigators that he used a mallet to hit the 75-year-old on the side of her head, knocking her unconscious, according to the probable cause affidavit.

Lachazo allegedly admitted to taking a chemical from the garage and then dousing Udell and the room with it, sparking a fire, according to the probable cause affidavit.

Udell was hospitalized in extremely critical condition on Monday. She died on Tuesday, said Boca Raton police.

Lachazo was charged with attempted second-degree murder, arson and aggravated battery with a deadly weapon on a person over 65 years of age, police said. Amended charges are possible following Udell's death, police said.

"We offer our sincere condolences to her family and loved ones," the police department said in a statement. "We will work with the State Attorney’s Office and the Medical Examiner’s Office as we continue to investigate."

The suspect worked for a company which was contracted to deliver the appliance for Best Buy, according to police.

"Beyond working with law enforcement in any way we can, we have suspended our relationship with the small, local company that was sub-contracted to deliver to the customer’s home," Best Buy CEO Corie Barry said in a statement.

"In the hours after we initially learned what happened, we immediately re-visited our delivery and installation programs and, in the coming days, will do two things: 1) ensure all our processes were followed and 2) work with our delivery partners to do anything more we can to help ensure that this type of tragedy will not happen again," Barry said. "Additionally, we are hiring an independent security firm to review our existing screening, audit and safety programs and share with us their assessment on how we can improve."

He is set to appear in court on Sept. 18. An attorney was not immediately listed.

ABC News' Matt German contributed to this report.