The investigation into the deadly stabbing of a beloved Burbank teacher continues as officers investigate the relationship between the suspect and victim, the Burbank Police Department said.

Sergio Fraire, 30, was charged with murder in connection with the deadly stabbing of 59-year-old Arti Varma, who taught at Bret Harte Elementary School. The suspect is also accused of stabbing the woman’s 25-year-old daughter, who survived the attack.

Police initially said Fraire’s sister, another educator at the same school where the victim worked, was under investigation, but later said that was not the case. Burbank police did say it’s investigating any possible relationship between Fraire and the victims.

“Detectives continue to investigate whether she had any involvement,” the department said of the sister to NBCLA on Friday.

Varma, a first-grade teacher, and her 25-year-old daughter were taken to a hospital after being stabbed. But Varma later died from her injuries, police said.

Fraire pleaded not guilty Thursday after being arrested for the stabbing.  Prosecutors alleged that Fraire personally used a deadly weapon, a knife, in the commission of the murder and attempted murder and personally inflicted great bodily injury upon the attempted murder victim.

Verma was described by school district officials as a “devoted and passionate” teacher who was committed to the education of her students at Bret Harte Elementary School.

Varma’s daughter remained hospitalized, but her condition was stable, police said.

Anyone with information was asked to contact the Burbank Police Department’s Investigation Division at 818-238-3210.