SPRING HILL — Before the fatal gunshots, Joseph Walter Medeiros seemed to fit quietly into the peaceful, well-manicured neighborhood of the Greens at Seven Hills.

Medeiros, 64, waved to his neighbors and tended to his gardens. Always friendly, he mostly kept to himself, said next-door neighbors William and Elaine Stapleton. The Stapletons, who were not woken up by Monday morning's gunshots, said the news was confounding.

"I know they always say, 'He was so nice, he was so quiet. ... But it's really true," Elaine Stapleton said Tuesday afternoon. "We are just shocked."

Early Monday morning, Medeiros shot his 44-year-old daughter, Nancy Walker, and his friend, Fernando Silva, during an argument, according to the Hernando County Sheriff's Office.

A roommate heard the commotion from her bedroom and attempted to disarm Medeiros, who grabbed a kitchen knife and stabbed Silva repeatedly, authorities said. The roommate called 911 at 3:46 a.m., and Medeiros waited for deputies outside.

Walker was pronounced dead at Bayfront Health Spring Hill. Silva, 58, was reported to be in intensive care earlier this week.

Deputies arrested Medeiros on charges of second-degree murder, attempted second-degree murder and aggravated assault with a deadly weapon.

He was booked into the Hernando County Detention Center and was being held without bail.

Authorities have not released a possible motive.

A day later, the Stapletons tried to make sense of the situation. The couple said they weren't acquainted with Walker, but they knew she was living with her father. She parked her silver Chrysler convertible in a foreclosed home's driveway across the street, they said, and Medeiros once introduced Walker to the Stapletons in passing.

The couple said they never heard fights between Medeiros and his daughter.

"He seemed like a very nice man," Elaine Stapleton said. "Something must have just snapped."

There was no indication that Medeiros could ever act out violently, she added. Medeiros does not have a criminal record with the Florida Department of Law Enforcement.

When Medeiros bought the home at 451 Rio Vista Court last year, the house was an eyesore, William Stapleton said. According to property records, Medeiros paid $176,900 for the house which, at the time, had a sandy yard and a black, moldy roof. The house was appraised at $145,979.

Irresponsible renters had let the house go, he explained. After years of settled retirement, the Stapletons were ready to pick up and move.

Medeiros worked hard to clean and restore the house, William Stapleton said.

On Tuesday afternoon, Medeiros' red four-door Dodge pickup sat in the driveway. Two small garage lights were still on, and a few of the flowers wilted in the sun.

"Walter was the reason we stayed," William Stapleton said. "I was thrilled to have him as a neighbor."

Staff writer Zachary T. Sampson contributed to this report. Contact Hannah Alani at halani@tampabay.com or (813) 909-4617. Follow @hannahalani.