Two teenage boys have been charged with murder following an investigation into the fatal shooting of 23-year-old university student Marco Tapia in Sydney's south-west.

Tapia was fatally shot inside his family's home in Glen Alpine, near Campbelltown, shortly before 4am on September 1. Emergency services were called to the property following reports of a home invasion, where officers found the university student suffering from a gunshot wound. He died at the scene.

Investigators subsequently determined that the property allegedly targeted by the offenders was the wrong house.

Following an extensive investigation, detectives from Strike Force Gareno executed search warrants at homes in Fairfield on September 16. Two boys, aged 14 and 16, were arrested and taken to Cabramatta Police Station.

Both teenagers have been charged with murder, participating in a criminal group contributing to criminal activity, possessing an unauthorised firearm and two counts of driving conveyances taken without the owner's consent.

The 14-year-old also faces an additional charge relating to damage to property by fire or explosion.

Police allege the teenagers were involved in activities connected with the shooting, including arranging vehicles and providing a firearm. Investigators allege they were part of a wider criminal operation surrounding the fatal home invasion.

Police have stated that the teenagers are not alleged to have fired the weapon that killed Tapia. Their murder charges relate to allegations concerning their participation in the broader criminal activity.

Both teenagers were refused bail and were due to appear before a children's court on September 17.

Tapia was a biomedical engineering student at the University of Technology Sydney. His death has prompted continued investigation into the circumstances surrounding the home invasion and the people involved.

Detectives are continuing to examine evidence gathered during the investigation as they work to identify and prosecute others who may have been involved.

The case remains before the courts. The charges against the two teenagers are allegations and have not been proven. Both accused are entitled to the presumption of innocence unless and until a court determines otherwise.

The investigation remains ongoing, with police continuing to examine the events leading up to the fatal shooting and the alleged roles of those connected to the incident.