National Bureau of Investigation Director Melvin Matibag on Thursday said investigators have identified a person of interest in the death threats made against Sen. Risa Hontiveros through social media.

Matibag said the NBI launched the investigation after Hontiveros' chief of staff sought the bureau's assistance. He added that the case is now under case build-up and may be referred to the Department of Justice if sufficient evidence is established.

"Like any other case that reaches our office, we will conduct the necessary investigation," Matibag said.

Hontiveros earlier disclosed that she had submitted to the NBI the names and screenshots of hundreds of social media users who allegedly threatened to kill her.

The senator said the threats intensified following the killing of political vlogger Alicia Lipata, also known as "Mima Alicia."

Lipata, a 24-year-old pro-administration vlogger known for her political commentaries and criticism of Vice President Sara Duterte and her allies, was fatally shot in Caloocan City on July 12.

The Philippine National Police has arrested two suspects in the case, although authorities have yet to establish the motive behind the killing.

Hontiveros said some online users not only celebrated Lipata's death but also posted messages claiming that she would be "the next" target.

"We are taking these threats seriously. My staff has routinely deleted and reported these disturbing comments on Facebook, and we have submitted to the NBI the names and screenshots of hundreds of Facebook users who have threatened to kill me," she said.

She also urged social media platforms and law enforcement agencies to act more aggressively against online threats, stressing that political disagreements should never escalate into incitements to violence.

"Threatening the lives of others must never become normal in our society. No matter how deep our political differences may be, our disagreements must have limits. We cannot allow such hatred to cost another life. We are better than this," Hontiveros said.