In September, that couple's 3-year-old boy was found on a stranger's porch.
WIVB-TV, a television station in Buffalo, reported that these suspects have been in custody for at least two months.
The station reported that they are being held on drug conspiracy charges, not murder charges.
The station has not yet named these suspects, while the investigation continues.
In New York district court transcripts, the U.S. Attorney's Office is reported to have clearly stated these defendants are believed to be "substantially involved" in the deaths of Miguel Valentin-Colon and Nicole Plaud.
The bodies of Valentin-Colon and Plaud were identified last month after they were found in a burned-out van on Sept. 16.
Among the evidence, the Buffalo station says federal investigators, who had already been watching the suspects, said a red car driven by the suspects had been around that van on multiple occasions.
They also said clothes found where the suspects lived matched clothing found in the victims' hotel room.
A friend, who traveled to Buffalo with the couple, is also missing.
Authorities are still working to identify remains found in a fire pit behind the suspects' residence in Buffalo.
Those remains were discovered a few days after police found the burned-out van.
The little boy who was found on a porch is safe with family in Central Florida.
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