Instagram star Dunka Raymond Caldwell, known as Humdinger, dies aged 30 after taking cocaine laced with heroin

The cocaine has been linked to the deaths of social media star Dunka Raymond Caldwell and also 43-year-old Angel Mounce-Stephens by police. Both died in separate house in Sydney, Australia, on Friday August 30.

Caldwell, aged 30, was known to his 60,000 followers as Humdinger, was found dead in his home in Glebe, Australia, early in the morning. Mounce-Stephens was found in her Newtown home later that morning at around 8.45am.

New South Wales (NSW) Police Strike Force Chatton has launched an investigation into the tainted batch of drugs, which is believed to have been cut with heroin and other opioids. “Police are awaiting the results of a post-mortem examination to determine the exact cause of their deaths”, a NSW Police spokesman said.

The deaths prompted an urgent warning from NSW Health, which said two others people had been taken to hospital after overdosing on heroin which had been sold as cocaine.

Caldwell's death prompted an outpouring of grief from Caldwell’s local area where he had become a beloved local celebrity. Writing on his Instagram page, where he had more than 32,000 followers, one fan said: “Such a bright personality just gone. There will never be another Humding. He was absolutely hilarious and wasn’t afraid to show vulnerability at times either. RIP brother. Rest easy!

A second said: “Rip easy my brother, see you in the dream time.” A third said: “Im in disbelief of this horrific news of your passing. May God lift you up and bring you into the light. Blessings upon you, the family and the entire community who looks up to you brother. My thoughts and prayers go out to you and all your loved ones.”

Caldwell was the uncle of professional rugby league player Tyrone Munro, aged 19, who plays for the South Sydney Rabbitohs, and the team recently donned black armbands in honour of late influencer.

Mounce-Stephens' funeral is understood to have previously struggled with substance abuse. She was once convicted of drug supply and possession and ordered to undertake rehabilitation, according to Daily Mail Australia. Her funeral was held at Rookwood Cemetery last week.

NSW Health confirmed that two other people have also been hospitalised after coming into contact with the tainted cocaine. The pair were treated for a heroin overdose after ingesting what they thought was cocaine.

NSW's Chief Addiction Medicine Specialist, Dr Hester Wilson, said it takes just “a single line” of heroin to prompt an overdose, as reported by Daily Mail Australia. “One of the dangers of illicit drug supply is the strength and contents of the substance you are getting is unknown and can be inconsistent”, she said. “It is important that people recognise the signs of an opioid overdose early and know how to respond.”

She explained that opioid overdoses can cause pinpoint pupils, drowsiness, loss of consciousness, slowed breathing, snoring, blue or grey skin, and added that it can be life-threatening, she said. She added: “Heroin and other opioids can be sold as or found in cocaine, methamphetamine, and MDMA (ecstasy). You cannot always tell the difference between these drugs by appearance.”

Wilson advised all drug users to carry naloxone, an opioid antagonist which can reverse the effects of an opioid overdose, on their person if they intend on using. Naloxone does not require a prescription and is free for anyone at risk of opioid overdose in NSW.