The police were called after residents reportedly saw blood on the building's front stoop, hallway and de la Plaza's doorknob. Police then found blood all over his apartment, where his body was found, stabbed three times in the neck, chest and stomach.
Bhushan said investigators' questions on the morning de la Plaza's body was found focused on whether he could have committed suicide. She said the police asked if he wrote poetry, was depressed or having girl trouble.
"It seemed to me a foregone conclusion of suicide and it seemed like they wanted to be done with it," she said.
When she suggested that all the blood inside and outside the apartment seemed incongruous with a suicide, she claims the police brushed aside her questions, saying, "suicide is an irrational act."
Nix and Murphy both said police officers have, as recently as a few months ago, told them they continue to think de la Plaza killed himself, though de la Plaza's father said at a press conference last week that police investigators told him they considered the case a homicide.
Nix said de la Plaza had no reason to kill himself. She said he had been promoted at work the day before he died and had gone on a date that night and then met friends to celebrate his promotion. He had money saved up and was planning to move to Argentina, she said.
"He had too much love for life," she said. "His goal was to travel, to look at art, to eat good food, to see his friends and family. He was curious and interested in everything."
She said she suspected that de la Plaza, who she said was going out on dates he'd met on online dating sights nearly every night, may have been killed by a romantic rival, or happened on a drug deal or robbery.
Murphy said he thought de la Plaza was followed home and attacked. "I think he was preyed upon," he said.
At the press conference last week, Francois de la Plaza credited the San Francisco police with investigating the case as a homicide but said, "I find it appalling that a Franco-American citizen who died here needed the help of the French police to be investigated. This happened in one of the richest countries, and one of the richest cities. I do not understand."