Two young teens have been charged with murder after a failed gangland hit resulted in the death of an innocent young man.

In a case of mistaken identity, biomedical student Marco Tapia, 23, was shot dead in his home on Mount Sugarloaf Dr in Glen Alpine in southwest Sydney at 3.40am on September 1.

A trail of evidence led detectives to a 14-year-old boy and a 16-year-old boy “early in the piece,” NSW Police Homicide Squad Commander Det. Supt. Joe Doueihi alleged at a press conference on Thursday.

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The teens, previously unknown to police, were arrested in their family homes in Fairfield on Wednesday.

“Both young, vulnerable, naive children. Both still at school. I’m at a loss as to why these people were enticed into this type of crime,” Doueihi said.

Two teen boys have been charged over the alleged murder of Marco Tapia, 23, in his Glen Alpine home. Credit: 7NEWS

He said the murder charges came as a shock to boys’ parents.

“The parents were devastated. They had no idea what was going on,” Doueihi said.

Doueihi said that the boys, however, were cognisant of their alleged crimes.

“We obviously allege, with the fact that we’ve charged them with murder, that they were aware of what their actions were,” he said.

“They were significantly involved in this crime.

“We will allege that the boys were involved in the preparation, planning and aftermath of the murders, by disposing the vehicles, supplying weapons, and cleaning the residence that the offenders occupied at the time.

“They (allegedly) picked up the offenders, they dropped off the offenders, they supplied the firearm, they burnt the car.”

He said the boys were paid in exchange for their alleged roles in the killing.

Tapia was an innocent biomedical student, killed in what has been confirmed by police as a case of mistaken identity with all the hallmarks of an underworld hit. Credit: 7NEWS

‘The bottom of the barrel’

The boys are accused of supporting three main offenders who remain on the run after allegedly entering Tapia’s home and firing the gun.

“Even though these boys were not present and part of the actual murder, we will allege that by the nature of their activities they form part of a joint criminal enterprise, therefore they are liable for the offence of murder,” Doueihi said.

“That’s why they’ve been charged with that offence.”

He said that the young alleged offenders left a trail of evidence behind them.

“The 14-year-old offender, as he attempted to burn the kill car, burnt himself in the process and ended up in hospital,” Doueihi said.

NSW Police Homicide Squad Commander Det. Supt. Joe Doueihi alleges organised crime bosses are hiring young teens to do their dirty work. Credit: 7NEWS

He said that the surge in young, “naive” recruits involved in underworld killings is the result of recent police crackdowns.

There have been more than 800 organised crime-related arrests and 2000 charges in the last few years, leaving crime bosses with a meager hiring pool, Doueihi said.

“They’re absolutley scraping the bottom of the barrel right now, and locating the young, vulnerable offenders,” he said.

“Unfortunately these young men that are being targeted (by criminal networks) are naive, they’re not aware of the consequences of their actions.

“They’re easily lured by the thrill and the financial incentive, but its a short-term gain for significantly long-term consequences.

“They potentially could spend a significant period of their lives in jail as a result of this.”

‘Cowards’ and the new face of gangland crime

Police said the current offshore string-pulling of organised crime bosses is a modern underworld development.

Doueihi called these offshore crime bosses calling the shots “cowards”.

“They run away from Australia and they get young kids to do their work. Man up.

“The environment has changed. We’ve seen this now over a number of years. We never saw this five to ten years ago.”

Doueihi referred to similarities between the hired youth’s accused of Tapia’s death, and the 18-year-old man charged with murder over the alleged mistaken identity killing of Joshua Macdonald, 40, in Merrylands West days after Tapia was shot dead.

Joshua MacDonald, 40, became the second murder victim killed in a case of mistaken identity in Sydney within days. Credit: 7NEWS

“In terms of chasing the upper eschelons of these organised crime groups, we continue to with our partners, onshore and offshore, to do that, and its progressing well,” Doueihi said.

Police are yet to determine the crime group involved in Tapia’s death, and are still searching for the three main offenders involved.

There have been developments in the probe investigating these main offenders, but Doueihi said the two teen boys have not played a role in helping police track them down.