The man, identified as Erwin Ching, died on the spot while the woman, Kristine Montiel, remains in critical condition. The two were both 22 years old.
Initial reports showed that Ching and Montiel shot themselves in the right temple inside the Anito Lodge in Sta. Mesa about 10 p.m. with a caliber .357 pistol.
Manila police homicide chief Senior Inspector Alejandro Yanquiling said they are still unaware of who was shot first but said the gun does not belong to any of the victims.
Police have identified the gun owner and is now conducting an investigation.
Ching died on the spot from his gunshot wound while Montiel, a student of Sienna College, is said to be in critical condition at the Lourdes Hospital.
Yanquiling said employees of the motel have issued an affidavit.
Police reportedly found two letters in the room occupied by the couple.
One letter supposedly was addressed to Chings mother thanking her, asking for forgiveness and hinting at his misery but did not elaborate.
He also asked that his belongings be given to a friend whose contact numbers were provided.
Yanquiling, however, could not confirm the existence of the supposed suicide note.
Another letter, also signed by Ching, was reportedly addressed to Anito management apologizing for the trouble and asking that their valuables be given to their respective families. Jose Aravilla