Faces and Voices of Recovery (Favor UK) wants Scotland to adopt the inquests system used elsewhere in the UK, in which a coroner examines the circumstances around sudden deaths.

The charity claims there is a “disturbing trend of reclassifying potential homicides as suicides or accidents”.

The Crown Office’s Scottish Fatalities Investigation Unit (SFIU) examines deaths. In some cases, fatal accident inquiries take place.

Favor UK’s CEO, Annemarie Ward, told the BBC’s Good Morning Scotland radio programme that the SFIU is not demonstrating enough thoroughness in its investigations.

She said: “We’ve noticed a disturbing trend where these deaths might involve foul play – are instead being labelled as suicides or accidents. And this not only masks the real issues but it also stifles the important discussions we need to have publicly.”

A spokesman for the Crown Office said: “We understand the impact that the loss of a loved one can have on bereaved families. The procurator fiscal will investigate every death reported to us thoroughly and independently.

“This work seeks to establish what happened and consider whether criminal proceedings or a fatal accident inquiry would be appropriate.

“It is a strength of the Scottish system, which reflects a common European model, that death investigations are undertaken by a public prosecutor, who in Scotland is the procurator fiscal.”