PORT-AU-PRINCE, Haiti—Haitian police said Friday that a fourth officer has been arrested in the killing of President Jovenel Moïse. National Police spokesperson Marie-Michelle Verrier said a total of 27 people have been arrested and others are still being sought in connection with the July 7 attack at the president’s home. Another nine officers were being held in isolation for questioning—apparently among a total of 44 people held to determine what responsibility they may have had in the killing or to determine if they were negligent in their duties. Authorities also asked for help from the general public. “Everyone the police is looking for, we are asking the population for help. … Give your participation, help us find these people”, said Verrier, who also mentioned there was a “big” reward for anyone who gives information that leads to the arrest of suspects, but did not specify the amount of the reward. …