Maria Aurora Moynihan, daughter of the third Baron Moynihan, was found shot dead in Quezon City, Manila in the early hours of Sunday September 11, police told CNN Philippines
A sign reading "Drug pusher to celebrities, you're next," was found next to her body.
Moynihan, 45, had previously been charged with illegal drug use after being arrested in a buy-bust operation in 2013, Quezon City Police Department Superintendent Guillermo Eleazar told CNN Philippines.
She was found in possession of cannabis, crystal methamphetamine and ecstasy, but was not charged with selling, Eleazar said.
"We ask the public at this time to respect our need for privacy so that we may continue to heal in our own way," Moynihan's sister, actress Maritoni Fernandez said in a statement published by local media.
"In the early hours of September 10th, we lost my sister Aurora Moynihan. We as a family have one priority and truth at this point in time and that is to protect her children from further pain and suffering so that they, and we as a family may take this time to grieve, mourn but most of all celebrate the life of this exceptional human being I will forever have the privilege of calling my sister," Maritoni said.
The sister's father, the late Antony Moynihan, moved to the Philippines in the late 1960s after a colorful career in which his chief occupations were "bongo-drummer, confidence trickster, brothel-keeper, drug-smuggler and police informer," according
to his obituary in the UK's Daily Telegraph.
In Manila, Moynihan was involved in the heroin trade as an associate of Sydney's "Double Bay Mob," according to a 1980 Australian Royal Commission report
on the drug trade.
Though never convicted of any drug offenses himself, Moynihan secretly recorded conversations
with notorious Welsh cannabis smuggler Howard Marks
for US authorities, leading to Marks' imprisonment.
Maria Moynihan's death is only the latest in an ongoing and bloody crackdown on the drug trade in the Philippines, launched by President Rodrigo Duterte.
More than 1,100 people have been killed by police in over 18,800 operations since June, according to official figures, with rights groups saying the amount of deaths may be hundreds higher.
In stunning testimony last week, a former hit man told a Philippines Senate hearing that he had been part of a death squad
that served under Duterte when he was mayor of Davao, targeting drug dealers.
On Monday, Senator Leila de Lima, a fierce critic of the crackdown who launched the hearings into it, was removed as head of the Justice and Human Rights committee