(UPDATED) South Korean businessman Jee Ick Joo, an alleged victim of a "tokhang-for-ransom" scheme, was killed by police officers inside the Philippine National Police headquarters in Camp Crame, the PNP chief said Thursday.

Jee was reportedly killed near the PNP community relations group office, which is near the PNP Press Office.

A source alleged that Senior Police Office 3 (SPO3) Ricky Sta. Isabel covered the victim's head with tape before he was strangled inside a black car.

Sta. Isabel on Monday sought voluntary protective custody at the National Bureau of Investigation.

PNP chief Director General Ronald "Bato" Dela Rosa said he will protest moves to make Sta. Isabel a state witness, saying the former is "most guilty" in the killing.

"Paano gagawing state witness ang pinaka-guilty? I strongly disagree and I will protest kapag ginawa nila iyon na state witness," he said.

The PNP chief also apologized to South Korea on Thursday for the death of Jee Ick Joo.

"I am very sorry na nangyari itong krimen na ito at mga tao ko pa yung involved. Kung sa kanila sa Korea, yung kanilang customs and traditions dun mag hara kiri sila sa sobrang hiya, ako hindi ko kayang gawin yan dahil masakit yan pag gagawin ko," Dela Rosa said during a press conference.

"Gusto [ko] lang mag disappear dito sa mundo dahil sa sobrang hiya dahil sa ginagawa ng mga tao ko," he added.

Dela Rosa said they are explaining the death of Jee Ick Joo to the victim's family and will give South Korea a proper explanation in "due time."

The Korean businessman went missing last year in Angeles City, before he was reported dead earlier this week.

His wife earlier said she paid millions in ransom for Jee's release but the kidnappers wanted more.

Authorities are also eyeing a former police officer turned funeral parlor owner as a person of interest in the case following reports that Jee's body was brought to his funeral parlor last year.

Caloocan Mayor Oscar Malapitan said Barangay 165, Caloocan chairman Gerardo Santiago, who owns the funeral parlor where Jee’s remains were found, flew to Vancouver on January 11 on board Philippine Airlines flight PR-118.

• READ: NBI confirms kidnapped South Korean's remains cremated last year

#BATORESIGN

Meanwhile, calls for Dela Rosa to resign as PNP chief trended Thursday on Twitter with the hashtag #BatoResign.

Netizens criticized Dela Rosa over the death of Jee which happened inside the police camp, with some giving emphasis on the issue of extrajudicial killings and police-related deaths brought about by the war on drugs. --with reports from Dexter Ganibe, DZMM

: Crocodile tears. Kung hindi foreigner yung pinatay, hindi pa magsisisi. #BatoResign

— STARBOY LOGRO (@Watdahel_Marcel) January 19, 2017

This Bato guy screams incompetence. Pure show-off lang naman. #BatoResign

— P🅰️U💪🏻 (@prince21paul) January 19, 2017

The late Mayor Espinosa was murdered inside City Jail. Now, Mr. Joo was murdered inside Camp Crame. #WowJustWow #BatoResign #AnoNaPNP

— Neil Bernales (@acbernales) January 19, 2017

#BatoResign Out of delicadeza, Bato should immediately vacate his position. #BatoResign WALANG GANITO SA SOUTH KOREA, JAPAN 👮👮👮 @PNPhotline

— gabriellaQATAR (@gabriellaQatar) January 19, 2017

A Korean national is the last straw, but before that there was Espinosa and thousands of others. Wag gawing raket ang krimen #BATORESIGN.

— COCO QUIZON l (@cocoquizon) January 19, 2017