Predator 2

In 1997, Los Angeles is suffering from both a heat wave and a turf war between heavily armed Colombian and Jamaican drug cartels. A Predator watches a shootout between the police and Colombians, observing as Lieutenant Michael R. Harrigan charges into the firefight to rescue two wounded officers and drive the Colombians back into their hideout.
While the police wait for a federal task force, the Predator crashes through a skylight and assaults the Colombians. Against orders, Harrigan and his police detectives Leona Cantrell and Danny Archuleta enter the hideout. They find the Colombians have been slaughtered. Harrigan pursues the crazed gang leader onto the roof and shoots him. He catches a glimpse of the camouflaged Predator but dismisses it as an effect of the heat and his acrophobia.
At the station, Harrigan is reprimanded by his superiors for his disobedience. He is introduced to Special Agent Peter Keyes, leader of the task force investigating the cartels, and Detective Jerry Lambert, the newest member of Harrigan's team.
Later that evening, several Jamaican cartel members enter the Colombian drug lord's penthouse. After they ritualistically murder him, the Predator kills them all. Harrigan's team enter the penthouse where they find the Jamaicans' skinned corpses suspended from the rafters, noting the similarity to the earlier Colombian massacre. Keyes arrives and kicks Harrigan's team out. Archuleta later returns to continue investigating. After he finds one of the Predator's speartip weapons in an air conditioning vent, the Predator kills him. Harrigan vows to bring down Danny's killer, believing they are dealing with an assassin.
Forensic scientist Dr. Irene Edwards finds the speartip does not correspond to any known element on the periodic table. Seeking answers, Harrigan meets with Jamaican drug lord King Willie, a voodoo practitioner, in an alley. King Willie tells Harrigan that the killer is supernatural, and that he should prepare himself for battle against him. Harrigan, even more puzzled, leaves the alley, and the Predator kills King Willie, whose head is made into a trophy; from thereon the creature begins to trail Harrigan.
Harrigan and his team hear about King Willie's death. Dr. Edwards tells them that she found some blood that came from the slaughter house where Keyes was last seen. Harrigan tells his team to meet him at the slaughter house to investigate. Cantrell and Lambert take the subway to rendezvous with Harrigan but get involved in a mugging on the subway until the Predator attacks them and the other armed passengers. Cantrell herds the passengers to safety while Lambert faces off against the Predator and is killed. The Predator prepares to kill Cantrell but releases her after a quick visual scan of her body reveals that she is pregnant.
Arriving on the scene, Harrigan chases the Predator but is stopped by Keyes' men. Keyes reveals that the killer is an extraterrestrial hunter with infrared vision that uses active camouflage and has been hunting humans for sport throughout armed conflicts, the recent one referring to previous events in Central America. Keyes and his team have set a trap in a nearby slaughterhouse, using thermally insulated suits and cryogenic weapons to capture him for study.
When the Predator arrives, the trap is sprung. However, the Predator uses his mask to scan through various electromagnetic wavelengths, locates and slaughters the team. Keyes is wounded, but Harrigan attacks the Predator, wounds him, and removes his mask. The Predator kills Keyes with a throwing disc and chases Harrigan to a roof. Harrigan knocks him over the side and finds himself on a narrow ledge with the Predator hanging below. The Predator activates the self-destruct device on his forearm. Harrigan grabs the throwing disc and severs the forearm, rendering the device harmless. The Predator falls through an apartment window, treats his wounds and flees through the building.
Harrigan follows him down an elevator shaft and finds a spacecraft in an underground chamber. Inside the ship, the two face off in a final duel, and Harrigan finally kills the Predator with the throwing disc. Several other Predators appear, collecting their dead comrade, and one of them presents Harrigan with an antique flintlock pistol as a trophy. Harrigan escapes from the ship as it takes off and reaches the surface just as the remainder of Keyes' team arrives. Harrigan knows that the creatures will return and continue to hunt on Earth as they have done for centuries.

Question: Who knows that the creatures will return ?
Answer: Harrigan; Harrigan