HOUSTON — For at least two days, neighbors at a city apartment complex noticed an acrid aroma, black smoke, and leaping flames coming from two barbecue grills on the balcony of a second-floor apartment.

What, neighbors at the Red Oak Place apartments wondered, was going on in the unit where 27-year-old Timothy Wayne Shepherd lived? What was he burning at all hours, for days at a time? The answer turned their stomachs.

According to law enforcement officials, Mr. Shepherd dismembered, and then burned the body of his former girlfriend, Tynesha Stewart, 19, a Texas A&M University student. Nothing remains of Stewart’s body, Harris County Sheriff Tommy Thomas said at a press conference Saturday.

“I just don’t know what to think about it,” said Louis Evans, whose balcony faces Mr. Shepherd’s in the quiet tree-lined enclave in northern Houston. “I thought he was a nice normal person. I guess you never know what your neighbors are doing.”

Authorities said Mr. Shepherd has confessed to strangling and dismembering Stewart, a college freshman who was home on spring break, because he was angry that she had started a new relationship.

Officials first thought Mr. Shepherd had disposed of her remains in a large commercial trash bin that had since been emptied, launching an intense debate in the area about whether the Sheriff’s Department should conduct a massive and expensive search of area landfills for Stewart’s remains.

Stewart was last seen March 15 and was reported missing March 19. The next day, the Harris County Sheriff’s Office homicide division launched its investigation.