The defiant mother of a man wanted in connection with the murder of a Pace University student refused to let the NYPD into her Manhattan apartment yesterday — and after a six-hour standoff it turned out he wasn’t even home.

That sent Warrant Squad cops scrambling to find Jimmy Siders, 31, indicted the day before on a second-degree-murder charge for his alleged role in the killing of Max Moreno, law-enforcement sources said.

Investigators believe Siders bought pot from Moreno at his Gold Street apartment, then left the door ajar so Randy Colon and Raymond Rizzo could enter and shoot Moreno in the head, the sources said.

Siders’ wheelchair-bound mother refused to open the door when police told her they had a warrant, police sources said.

That led to an hours-long standoff that closed down traffic.