NSW meth lab murder accused behind bars

A man has spent his first night behind bars accused of a double murder in a Sydney meth lab, which he allegedly carried out at the behest of a drug syndicate's top woman.

Kevin Ly allegedly murdered Son Thanh Nguyen, 39, and his girlfriend Thi Kim Lien Do, 35, in 2013 before wrapping their bodies in bedsheets and dumping them in separate locations.

Investigators believe Mr Nguyen was a methamphetamine "cook", and that he and Ms Do were murdered inside a Canley Vale rental home that doubled as a clandestine laboratory.

Ly, 25, appeared at Fairfield Local Court on Tuesday and did not apply for bail.

Earlier in the day, Detective Superintendent Mick Willing told reporters more arrests were expected.