MANILA (UPDATED) - A DNA sample taken from one of 5 victims in the San Jose del Monte, Bulacan massacre has matched the DNA of primary suspect Carmelino Ibañez, police said Friday.

A laboratory report from police Scene of the Crime Operatives said DNA found from a vaginal swab of the body of Mrs. Estrella Dizon was a match for Ibanez.

The DNA of 4 other persons of interest, however, did not match the sample from the victim.

It said a knife found inside the house of the victims was also used on 4 of the victims, lab analysis showed.

Police said this means that another murder weapon used in the killing has yet to be found, and that there could be more than one perpetrator.

Meanwhile, authorities said they will continue to investigate Dexter Carlos Sr, husband of Estrella, who was at work when the incident allegedly happened.

Based on the DNA results, it is unlikely that Carlos is a suspect in the crime, police said.

Ibañez, a 26-year-old construction worker, earlier admitted killing the 5 including three children aged 1, 5 and 11 while he was high on drugs. He earlier said he raped both Estrella and her mother, Aurora Dizon.

He later recanted his confession and said he was tortured by police to admit the crime.

Ibañez earlier tested negative for drug use after the crime.

For his part, Central Luzon police director Chief Supt. Aaron Aquino denied that Ibañez was tortured. With a report by Doland Castro, ABS-CBN News