Kenneth Iwamasa, 59, made the confession in a set of plea agreement papers he signed after he and four others were arrested in connection with supplying the drugs that killed the actor.

The papers show the injections were administered by non-medically trained Iwamasa from 8.30am on the day Perry died in the hot tub of his Pacific Palisades mansion in Los Angeles.

They say after the first dose, Perry's assistant gave him another one four hours later – and yet another 40 minutes later.

It was before the third injection Perry told him: “Shoot me up with a big one.”

The actor is said to have then told Iwamasa to start up the hot tub where his assistant later found him dead with his head in the water after his employee went to run a set of errands.

Perry's words were revealed as his stepfather Keith Morrison spoke out to say he hoped “unscrupulous suppliers of dangerous drugs will get the message”.

“We were and still are heartbroken by Matthew’s death, but it has helped to know law enforcement has taken his case very seriously," he said in a statement issued to Entertainment Weekly.

“We look forward to justice taking its course and we’re grateful for the exceptional work of the multiple agencies whose agents investigated Matthew’s death.

“We’re hoping unscrupulous suppliers of dangerous drugs will get the message.”

Matthew’s doctors have also been accused of abusing their “position of trust".

DEA Administrator Anne Milgram said Perry’s journey began with unscrupulous doctors who abused their position of trust because they saw him as a payday, to street dealers who gave him ketamine in unmarked vials.

Others arrested in relation to his death were doctors, Mark Chavez and Salvador Plasencia along with Jasveen Sangha and Erik Fleming.