By Peter D'Oench

MIAMI (CBSMiami) – The Federal Bureau of Investigation has joined the search for a newborn baby who disappeared after his mother, grandmother and great-grandmother were fatally shot in Southwest Miami-Dade.

On Tuesday, authorities shifted their search investigation to Collier County.

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It’s not clear how those in law enforcement picked this area to search, but it is close to the path that Ernesto Caballeiro took from southwest Miami-Dade to Pasco County. The area, north of Tampa, is where the baby’s father took his life.

This area has been part of a massive search for a few days and many are making it their mission to find baby Andrew.

“Just the story about how this baby was missing. I don’t know. I felt like it was the right thing to do,” said search volunteer, John Nicholas.

Nicholas is among dozens of volunteers joining those in several law enforcement agencies searching through and around these remote, wooded areas in Collier County for baby Andrew Caballeiro.

“There was a post on Marco Island Patriots, which is a Facebook group looking for volunteers and it tugged on my heart to come on out here and see if I could help.”

“It’s just that I feel it would be nice to find clues and help that’s all.”

Authorities say Ernesto Caballeiro took one-week-old Andrew from his southwest Miami-Dade home last Tuesday after killing Andrew’s mother, grandmother, and great grandmother.

They say his white van was found Wednesday north of Tampa, where he shot and killed himself.

The site of the search is near US 41 on State Road 29 along the route that Caballeiro took to Pasco County.

Nicholas told us he’s looking for any signs of Andrew, including diapers.

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“It’s just a group of everyone and we hope we have luck taking our time and doing our best searching.”

Texas EquuSearch and a team of more than 30 people from Peace River K9 Search and Rescue have been searching as well.

“We’ve got airboats, horses, we got dogs, we got the ground searchers,” said Texas EquuSearch founder Tim Miller.

“Time is not on our side. We’ve got a tiny, tiny baby and we know the animal alligator activity and stuff could certainly hinder what we are doing.”

This mission includes investigators who have assisted in high profile cases including the search for Caylee Anthony. It is an impressive site to residents like Lorraine Burgess.

“I hope that they find what they are looking for because for that to happen to that little baby I pray for the family and for them to find him safe because I got grandkids myself,” said Burgess.

Miami-Dade police are the lead agency and they tell me the search so far has found no signs of baby Andrew.

Baby Andre’s loved ones in southwest Miami-Dade have pleaded for people to come forward if they know anything.

Family and friends made their way into the Memorial Plan Funeral Home on Coral Way on Tuesday night. They gathered to pay respects to those killed.

Some relatives have come to South Florida from Cuba.

The three women will be buried on Wednesday.

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The family created a GoFundMe page to help pay for funeral costs.

Peter D'Oench