There was nothing out of the ordinary about the evening of April 25, when Renato Da Rocha, a 48-year-old Island carpenter and native of Brazil, disappeared into thin air.

A late afternoon rain shower had come and gone, leaving the Island cloaked in a misty fog. Mr. Da Rocha had spent the day doing exterior work on a home on Chappaquiddick, and he caught a ride back to his home on Curtis Lane in Edgartown from a co-worker.

According to police accounts, the two men exchanged a quick goodbye with little fanfare, each assuming they would see each other in the morning for work. Mr. Da Rocha then went inside the home he shared with several other people, all of whom were natives of Brazil.

It was the last time Mr. Da Rocha would ever be seen in public.

Now, almost six months after Mr. Da Rocha's disappearance, there remains no sign of him either dead or alive. Everyone who knew Mr. Da Rocha, including his family in Brazil, says they have not heard or spoken to him since first he went missing. But there are questions surrounding his disappearance.

Most of the questions center around one of Mr. Da Rocha's roommates, a man named Daglio Alberto Pinto, who left the Island and returned to Brazil under curious circumstances in the days following Mr. Da Rocha's disappearance.

Mr. Pinto is believed to be the last one to see Mr. Da Rocha alive, and police claim he withdrew a large sum of money from Mr. Da Rocha's bank account, using his checkbook, before he fled to Brazil.

Although police officials have stopped short of calling Mr. Pinto a suspect in any crime related to Mr. Da Rocha's disappearance, they have called him a key person of interest in the investigation. State police have been in contact with Interpol, the International Criminal Police Organization, and they are going through channels to contact and possibly extradite him.

But because the United States does not have an extradition agreement with Brazil, police officials are unsure when they will get to question Mr. Pinto, if at all.

Officially, state police and the Cape and Islands district attorney's office say that the investigation is ongoing, but sources close to the case said last week that the investigation is essentially in a holding pattern until police can contact Mr. Pinto or find Mr. Da Rocha.

While the investigation initially focused on looking for a missing person, police shifted their efforts to recovering a body in June. They used specially trained police cadaver dogs to search several areas including an area around Mr. Da Rocha's home, a beach area around Norton Point and an area near Katama Farm.

The search turned up nothing.

State police Sgt. Jeffrey Stone said investigators have studied records from the Steamship Authority and the airport, and have found no indication that Mr. Da Rocha ever left the Island.

"I guess it's possible he got in a rowboat and rowed over to Falmouth, but that's highly unlikely. We're talking about someone who showed up for work every day for years - and who sent money back to his family in Brazil on a regular basis. It doesn't make sense that he would just up and leave without telling anyone anything," Sergeant Stone said.

He said, among other things, that police found Mr. Da Rocha's truck parked in its usual spot at his house, and all his clothing and belongings were in place, as was the money in his bank account.

Mr. Da Rocha's disappearance is surrounded by an eerie silence on an Island where cases of missing persons and foul play are extremely rare. Although police have pursued the case with diligence, Mr. Da Rocha's disappearance has gone largely unnoticed. He has no family on the Island.

Many members of the Brazilian community are reluctant to talk to police or draw attention to themselves. There have been no letters to the editor, no candlelight vigils, no public cries for justice over Mr. Da Rocha's disappearance.

Mr. Stone said some in the Brazilian community may be here illegally, or may not be accustomed to calling police when there is a problem.

"In Brazil, many people will not call police when something goes wrong. They prefer to take care of things on their own. Its a cultural thing," he said.

This cultural divide has created the biggest obstacle in the investigation: friends and co-workers of Mr. Da Rocha did not report him missing for a full ten days, which allowed Mr. Pinto to leave the country before police could detain him for questioning.

Mr. Da Rocha was last seen on April 25, but was not reported missing until May 5.

In the interim, Mr. Pinto allegedly used Mr. Da Rocha's checkbook to withdraw money from the Sovereign Bank branch at the Triangle in Edgartown on two occasions, Mr. Stone said. Both times, Mr. Pinto persuaded someone to cash one of Mr. Da Rocha's checks.

Mr. Pinto reportedly convinced the unwitting accomplice that the check was drawn on his account, and that he needed help cashing it because he lost his identification. Eyewitnesses reported Mr. Pinto was outside the bank both times the checks were cashed, Mr. Stone said.

On one occasion, Mr. Pinto grew impatient and went inside the bank to see what was taking so long, at which time he was caught on tape by bank security cameras, Mr. Stone said.

Although investigators have been reluctant to name Mr. Pinto as a suspect in a possible murder, there are other incriminating facts against him. Several eyewitnesses told police that in the days leading up to Mr. Da Rocha's disappearance, he and Mr. Pinto were involved in a series of altercations.

But because police were not called at the time of the altercation, investigators have only been able to gather information after the fact.

Cape and Islands assistant district attorney Laura Marshard said she was unable to reveal specifics about the investigation because it is ongoing. She did, however, issue a plea for anyone with information about Mr. Da Rocha's disappearance to come forward and talk to police.

"I can't speak to this case specifically, but of course, any investigation relies on information from people who know what happened. If nobody comes forward, then the investigators have to work all that much harder," Ms. Marshard said.

Sergeant Stone encouraged anyone who might have information that would help the investigation to contact state police at 508-693-0545.