LYNN – The National Center for Missing and Exploited Children is focusing on Massachusetts and Puerto Rico in its bid to locate Giovanni Gonzalez, even as the boy’s mother held out hope Thursday that her son may be on the Caribbean island.Giovanni, 5, reportedly expressed interest in visiting a sibling in Puerto Rico and Daisy Colon said she reached out to family members on the island to see if they have any information about the missing boy.”I’m hoping he’s with a friend I don’t know about,” Colon, an East Boston resident, said.The Center began distributing color posters of Giovanni Tuesday with his description and police contact information in hotels, motels, fast food restaurants and other locations.It is also working with Wal-Mart to display posters on bulletin boards in the retail chain’s New England stores. Center senior case manager Gary Gardiner said one out of six missing children displayed on Center posters are found.The Center has classified Giovanni’s disappearance under the category “lost, injured or otherwise missing.””We have no idea where he is, that’s why we put him in that category. We’re looking for any and all information even if you think it is insignificant,” Gardiner said.The Center’s hotline number is 1-800-THE LOSTColon dropped off her son with the boy’s father, Ernesto Gonzalez, last Friday at 5 p.m.”I told Giovanni, ‘If you need anything, I’ll get it for you.’ He said, ‘No, Papi will get it; he’s getting me a ball,'” she said.Colon could not contact Gonzalez when she went to retrieve her son last Sunday at 8 p.m. in his Brightwood Terrace apartment located a block from District Court.She called police who questioned Gonzalez in his apartment. He told them he had not seen his son since Aug. 10. They arrested him and charged him with child endangerment after checking Colon’s cell phone and verifying she had spoken with Gonzalez on Aug. 15.Colon on Thursday said she does not know anyone close to Gonzalez who she can question regarding her son.”Ernesto is not sociable; he’s always by himself.”Gonzalez’s neighbor Kim Whitford said Gonzalez moved to Brightwood Terrace six months ago and rarely stopped to chat with neighbors as he carried his bicycle up to his second floor apartment.”I said hello to him but he had that look on his face – ‘Don’t talk to me.'”Whitford never saw Giovanni with his father, but other neighbors saw father and son playing with a ball Saturday afternoon and heard the boy laughing as he watched television Saturday evening.Police asked Brightwood residents for permission to search their apartments Wednesday even as they conducted a detailed search of downtown and crisscrossed the city with a helicopter.”Detectives went through the whole building,” Whitford said.