LYNN – The mother of a boy missing since last August wants to establish a reward for information on his whereabouts.”We’re going to try to shoot for $5,000. I’ll make up the difference on my own if I need to,” Daisy Colon said Tuesday after reasserting she believes her son, Giovanni, 5, is being held against his will by someone who knows the boy’s father, Ernesto Gonzalez.Colon said her hopes were stunningly confirmed late last September when she spotted Giovanni walking into High Rock Park with a man as she was driving on Essex Street. She said she parked her car and pursued the man but experienced an asthma attack intensified by anxiety as she started up the steep path.”I froze,” she said, adding she managed to summon two police officers who qu-estioned people in the vicinity of the park wi-thout success.”You don’t mistake your own son,” she said.She is now working with family and friends to organize a raffle and said the East Boston firm that manages her apartment building has offered to vouch for the reward’s authenticity once details are pinned down.Colon also plans to consult with detectives active in the search for her son before she schedules the raffle and announces reward details.”I’ll ask them how they want me to go forward,” she said.Authorities are still searching for the boy. They have not confirmed or discredited Gonzalez’ Nov. 27 published confession in which he claimed he killed his son after losing his temper, dismembered the boy’s body and dumped the body parts in three Dumpsters located across Lynn.The 36-year-old meat plant worker pleaded innocent last December to charges of kidnapping his son and misleading police investigating the boy’s disappearance. He has been held in the Essex House of Correction in Middleton since Aug. 18, a day after Colon went to pick up Giovanni at Gonzalez’ downtown apartment.She brought Giovanni from her home in East Boston to Lynn to see his father on Aug. 15 but Gonzalez told police he had not seen the boy since the previous weekend. Police initially charged him with child endangerment after Colon displayed to officers information on her cellular phone indicating she called Gonzalez the day she dropped her son off.Although Colon and Gonzalez were working out arrangements for Gonzalez to see the boy on a regular basis prior to Giovanni’s disappearance, Colon thinks Gonzalez “wanted Giovanni for himself” and arranged the boy’s abduction.Colon’s hopes of finding her son were bouyed in the initial months of the search when The Center for Missing and Exploited Children launched a campaign in Massachusetts and Puerto Rico seeking the public’s help in finding the boy. Clear Channel joined in the search by displaying Giovanni’s face on a Wyoma Square billboard.Colon on Tuesday said she did not stress her view on her son’s abduction in the initial months of the investigation because she did not want to steer attention away from police efforts to find Giovanni. Gonzalez’ confession prompted her to let people know she thinks her son was abducted.”I want to make sure no one forgets because he is alive,” she said.