NEW HAVEN, Conn. — Call it sympathy for the devil.

Jurors in the home-invasion murders of a Connecticut nurse and her two daughters must return for a second day of death-penalty deliberations today, because an unknown number of them are determined to spare the life of monster Stephen Hayes.

The looming possible deadlock left Hayes smiling broadly. Meanwhile, the attack’s sole survivor, Dr. William Petit, and his supporters left court solemnly, after exchanging grim hugs in the hallway of New Haven Superior Court, where Hayes has been on trial for two months.

Jurors are deciding if Hayes gets lethal injection or life without parole for raping and strangling Petit’s wife, Jennifer Hawke-Petit, and for helping to burn alive the couple’s daughters, Hayley, 17, and Michaela, 11.

Jurors have been told they’ll work today and tomorrow if needed.