BOSTON -- Officials searched an area near a pond in Lynn Thursday for a missing 5-year-old boy whose father has been arrested and charged with child endangerment.

Giovanni Gonzalez been missing since Monday, when the boy's father, Ernesto Gonzalez, 36, of Lynn, failed to return the boy to his mother, according to police.

Giovanni was brought by his mother to his father's home at 2 Brightwood Terrace in Lynn on Friday for a weekend visit. Police said Gonzalez did not return Giovanni to Daisy Colon, 22, of East Boston, at the end of the weekend.

Crews sectioned off an area near Flax Pond on Thursday, where officials continued to search. Since Monday, officials have searched Lynn neighborhoods, businesses, Dumpsters and a wooded area near the pond.

"The focus remains in the immediate vicinity to this police station and the neighborhood of the defendant's house," prosecutor John T. Dawley said. "I will say that at this point, we want to remain optimistic for this family that we can find him. I have no evidence that reflects that anyone other than the father is the person we have to focus on."

Gonzalez was arrested Monday and ordered held on $500,000 cash bail following his arraignment in Lynn District Court. Officials were concerned because Gonzalez had a cut on his left finger, and he gave conflicting accounts of how the injury happened, the Lynn Daily Item reported.

On Wednesday, Colon made an emotional plea for her son's return.

"Giovanni, please just say your name. I don't know what else to tell you. I miss you, honey. I miss you so much. My heart is breaking right now, honey. Please come home, and if you are with somebody and that person is listening, please make your heart open, you know. He is a wonderful kid, and anybody would love him. Please don't harm my kid, and let him free," Colon said.

Giovanni weighs approximately 40 pounds and is 49 inches tall with black hair and brown eyes. When last seen, he was wearing blue denim jeans, a red T-shirt, a silver braided chain and black Spider-Man sandals. He was carrying a black backpack that had the Transformers robot characters on it. It contained some of his clothes and toys.

He has a faded skin pigmentation mark on the lower right side of his chest and a small scar above his eyebrow.

Anyone with information about the child's disappearance or whereabouts is asked to call 911 or Lynn police at 781-595-2000.