MANILA- A 22-year-old man died while in detention due to multiple blunt force trauma, his death certificate showed.

A copy of Genesis "Tisoy" Argoncillo's death certificate showed that he died due to multiple blunt force trauma to his neck, head, chest and upper extremities, contrary to police claims the man died of natural causes.

Argoncillo was initially arrested last Friday in Novaliches, Quezon City as part of the anti-loitering campaign because he was not wearing a shirt.

Four days later, his family found him dead in a morgue, swollen and allegedly bearing marks of beating, they said.

• 'Binaboy nila kapatid ko': Family seeks justice for man allegedly beaten to death in detention

The Quezon City Police on Thursday denied that Argoncillo was beaten to death while in detention, saying the doctor who attended to the 22-year-old "certified that there were no signs of external injuries."

• QC cops deny detainee was beaten to death

Fearing a possible whitewash of the autopsy results, Argoncillo's elder sister Marilou is seeking the help of the Public Attorney's Office for a separate autopsy on her brother's remains.

"Parang awa niyo na tulungan niyo po kami. Sobra-sobrang perwisyo sa buhay namin," Marilou, the elder sister of Argoncillo, cried to ABS-CBN News.

"Ma'am Acosta, nagmamakaawa ako sa sinapit ng kapatid ko. [Sa] Crame kasi pina-autopsy baka manipulahin nila. Ikaw po sana gumawa ng sariling autopsy," she added, addressing PAO chief Persida Acosta.

(Please help us. This is too much damage in our lives already. Ma'am Acosta, I am pleading for justice for my brother. His remains were autopsied in Camp Crame and I fear that they might manipulate it. Please conduct a separate autopsy.)

ABS-CBN News has reached out to Acosta but she has yet to respond.

-reports from Angel Movido and Patrick Quintos, ABS-CBN News