A family of four was gunned down execution-style along a dark and deserted stretch of highway. Each was lying down or kneeling, and the mother was clutching her two young sons.

Authorities announced Friday it was no random act of violence, and that the Escobedos fell prey to a dangerous drug trade. The suspected killer was in custody, they said.

Jose Luis Escobedo, 28, was likely involved in cocaine trafficking, and he and his family were killed "for drugs, money or both," Sheriff Ken Mascara said.

The suspect was among three men and a woman who were arrested Wednesday on drug charges and are "persons of interest" in the killings, Mascara said. None had been charged with the slayings, and another man is being sought, he said.

The sheriff identified the drug suspects as Danny Varela, 26, Liana Lopez, 18, and Daniel Troya and Ricardo Sanchez, both 23.

A fifth man, Juan Gutierrez, was arrested and charged in the drug case but is not named as a person of interest in the slayings. He told authorities he and Varela were at the Escobedos' home before the killings and helped destroy drug packaging materials, according to court papers.

The five made their initial appearances in federal court Friday in Fort Pierce, said Jeannette Moran, a Drug Enforcement Administration spokeswoman. A bond hearing was set for Nov. 3. All the suspects have lengthy criminal records, including arrests for burglary, drugs and weapons possession.

Escobedo, his 25-year-old wife, Yessica Guerrero Escobedo, and their sons, Luis Julian, 4, and Luis Damian, 3, were found shot to death Oct. 13 along Florida's Turnpike near Port St. Lucie, about 50 miles north of their home in the Palm Beach County city of Greenacres.

Police searching the home after the killings found evidence that the father was involved in drug trafficking, Drug Enforcement Administration agent David Weeks said in court papers filed Friday. The items were said to include "suspected drug ledgers" and plastic packaging used to wrap illegal drugs.

Investigators linked the drug suspects to Escobedo through references in the ledgers, among other things, Weeks said.

A search of the West Palm Beach home where three of the men under arrest were living turned up suspected cocaine, Ecstasy and drug packaging materials, the DEA agent said. Investigators also found more than a dozen guns, including an AK-47 assault rifle. Weeks did not say if the weapons were used in the killings.

There also was a photograph of Escobedo with one of the suspects, according to court papers.

The sheriff would not say which of the suspects is believed to have shot the family. But he told The Associated Press that it appeared those responsible for the killings were in custody.

"Indications are that there may be homicide charges filed," said Troya's lawyer, Ruben Garcia. "That's all I can tell you right now."

Lopez's attorney, Ronald Chapman, said he had just been assigned the case and wasn't prepared to comment. Messages left for the other suspects' attorneys were not returned.

Investigators believe the family's Jeep was pulled to the side of the highway and that someone inside the vehicle shot the family and drove away. The Jeep was found abandoned in West Palm Beach three days later.

The family had moved to Florida in June from the Brownsville, Texas, area.

The sheriff said Escobedo's brother was involved in a heroin ring and is believed to be a fugitive in Mexico.