The FBI has joined the search for a newborn baby who disappeared after his mother, grandmother and great-grandmother were fatally shot in South Florida, possibly at the hands of his father, who later killed himself.

FBI spokesman Michael Leverock confirmed the agency is assisting in the case on Monday.

Andrew Caballeiro was a week old when his father, Ernesto Caballeiro, 49, kidnapped him last month, Miami-Dade police said.

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Florida police have found the body of 49-year-old Ernesto Caballeiro (left) who matches the description of a father sought by authorities in the disappearance of his infant baby, Andrew (right)

Police believe Cabelleiro kidnapped his son after killing the baby's mother, Arlety Garcia Valdez (center), 40, her mother Isabel Valdés González, 60 (right), and her grandmother, Lina González Licor, 84 (left)

Authorities found Caballeiro's body in a wooded area on Wednesday but they didn't find Andrew (pictured)

A short time later, police found the bodies of the mother of Caballeiro's baby, Arlety García Valdés, 40, her mother, Isabel Valdés González, 60, and her grandmother, Lina González Licor, 84.

Police suspect Caballeiro murdered the three women and went on the lam with his newborn son.

According to the description of a GoFundMe launched by the victims' relative, the three women died protecting the baby boy from his gun-wielding father.

Family members described Caballeiro as a troubled person and said he had a rocky relationship with Garcia Valdez, pictured above during one of her two known pregnancies

Andrew's nine-year-old sister was unharmed, according to relatives.

Family members said Caballeiro was a troubled man who had a rocky relationship with Garcia Valdez, reported Local10.

'I don’t expect anything good from him, I don’t expect any kind of generosity from him, including with his own son,' Melchor Izquierdo told the station. 'You’re dealing with a very sick, probably very crazy individual.'

Family members have asked Sen. Marco Rubio, a Republican from Florida, for special visas to allow relatives to travel from their native Cuba to the US to attend the women's funerals.

NBC Miami reported that the victims' loved ones have hired a private investigator to assist in the search for the missing baby.

Officers were called to the home after a family member stopped by the residence.

The relative had made several unsuccessful attempts to contact the family and found the bodies of the three women, Lee Cowart, a spokesman for Miami-Dade police said.

Police in Florida have been scouring the area in search of the missing child for the past week

Searchers are seen combing through a field in hopes of locating the newborn

The last known contact the women had was at about 10.30am that day, police said.

Police said Caballeiro lived at the four-bedroom home in the 21900 block of Southwest 187th Avenue where the triple homicide happened.

A day later, Caballeiro was found dead from an apparent self-inflicted gunshot wound inside a white van in Pasco County, which is north of Tampa. Baby Andrew was not found near his vehicle or body.

'Our detectives are still following all the leads they have in the case,' Miami-Dade police Detective Ángel Rodríguez said. 'We have the assistance of the Florida Department of Law Enforcement and the FBI, but at this time there’s been no change in the investigation.'

Authorities are searching locations where Caballeiro might have taken the baby after he left the rural Miami-Dade house where the three women were murdered.

Pasco County Sheriff Chris Nocco said during a news conference that K-9 units searched the wooded area near the van (pictured) and found Caballeiro with what appeared to be a single, self-inflicted gunshot wound from a rifle

Deputies searched the area between Blanton and nearby Interstate 75 last week.

'All we care about right now is that we get that baby back,' Pasco County Sheriff Chris Nocco said, adding that authorities are hoping Caballeiro handed the child off to someone else.

Police said their investigation has revealed that Caballeiro left the Miami Dade County area about 'four and half hours before arriving at the location in Pasco County, and was only in this location minutes before fatally shooting himself' with a rifle.

State records obtained by Miami Herald indicate that Caballeiro had been in trouble with the law before, including in 2004, when he was charged in connection to a string of car thefts. He ended up pleading guilty to a single count of grand theft and was sentenced to probation.

On Tuesday, authorities found the three women, who were all Hispanic and aged between 40 and 80, dead from gunshot wounds inside a home (investigators at the scene) in a remote neighborhood in south Miami-Dade

Lee Cowart, a spokesman for Miami-Dade police (above), said Caballeiro was related to at least one of the women found killed, but had not been named as a suspect

Authorities also shared a map that suggests the most likely route of travel for Caballeiro. Officers have urged anyone along the route to report any sightings or information to their local law enforcement

The infant is described as white, Hispanic, with black eyes, measuring 20 inches and weighing about seven pounds.

Authorities also shared a map that suggests the most likely route of travel for Caballeiro.

The white van has decals saying 'Nesty School Services' and 'Caution: Transporting Children.'

Officers have urged anyone along the route to report any sightings or information to their local law enforcement.

Anyone with information should call Miami-Dade Crime Stoppers at (305) 471-TIPS, or to call 911.