Two women from Ontario were never suspects in the slaying of a Canadian couple at a Mexican resort, the lead investigator now says.

Kimberley Kim and Cheryl Everall of Thunder Bay are only potential witnesses in the murder of Dominic and Nancy Ianiero, Bello Melchor Rodriguez told CBC News on Thursday.

The attorney general for the state of Quintana Roo also denied that four employees of the five-star resort near Cancun are the prime suspects in the deaths of the vacationing couple from Woodbridge, Ont.

Nancy and Dominic Ianiero.

Mexican media have reported that the two cleaners and two security guards, who haven't returned to work since the Ianieros' bodies were discovered, are being sought for questioning.

Lawyer Lee Baig, who represents Kim and Everall, said his clients are relieved to hear Rodriguez's statement. However, he added, they want Canadian police to reassure them that they're not on the suspect list.

"We want somebody in authority to clearly say this was a mistake," said Baig. "Then we breathe a sigh of relief."

The murdered couple's son, Anthony Ianiero, gives a statement to reporters in Woodbridge, Ont., a few days after his parents' death. (File Photo)

Kim and Everall were staying down the hall from the room where the Ianieros' bodies were found on Feb. 20. The Woodbridge, Ont. couple were in Mexico for their daughter's wedding when they were killed.

A bloody trail between the two rooms is at the centre of a forensic investigation.

Rodriguez, who has come under plenty of criticism over how the investigation has been conducted, said "it's a lie" that the two hotel rooms where blood and bodies were found were not protected so that they could be examined for crime scene evidence.

The adjoining rooms are still sealed off, he said, and only authorities are allowed inside.

Family members being interviewed in Canada

Meanwhile, Canadian police are interviewing Ianiero family members who travelled to Mexico for the wedding of the murdered couple's daughter Lily.

Mexico authorities also questioned family members before they left Mexico, and asked them to submit DNA samples.

DNA samples were also taken from hotel workers who may have had contact with the couple.

Two senior RCMP officers are in Mexico to help with the investigation, and they are expected to offer their expertise when forensic evidence found at the crime scene is examined.

Gabriela Rodriquez, tourism secretary for Quintana Roo, said police briefed her about a strand of hair found in Nancy Ianiero's hand.

• RELATED STORY: Mexican officials expect hair analysis in Ianiero case 'very soon'

"We were told a few days before that some evidence on the body of the murdered couple was found," she told CBC News.

Mexican authorities said they will release DNA testing results as well as tests done on forensic evidence in the coming days. They said they will discuss any leads with Canadian consular officials on Friday.