Before Nathan Carman's arrest, the circumstantial evidence against him was obvious for many years. He was accused of murdering his mother off New England and plotting to inherit millions.

The Vermont federal prosecutors aren't commenting on when they decided to present the case before the grand jury. And the indictment provides no clues or new information about the case that included a dramatic rescue at Sea and the suspicious deaths two members of a New England wealthy family.

According to legal experts and law enforcement officials, the delay in filing a criminal case could result from several factors. For example, his mother and boat were never found.

Jessica Brown, who was formerly a federal and state public defender and is now an assistant professor at Vermont Law School, said that it is very difficult to indict murder federally.

Indictment by the grand jury charges Carman, 28 years old, from Vernon, Vermont with murder and fraud in the death of his mother, Linda Carman. The incident occurred during a fishing trip that started in Rhode Island. Carman was discovered alone on a liferaft in Massachusetts near Martha's Vineyard eight days after his mother and father left port.

He is also accused of shooting John Chakalos, his millionaire grandfather, in Connecticut in 2013. However, he is not charged with this killing. He repeatedly denied being involved in either of the deaths.

Federal prosecutors claim that Carman's mother and father's deaths allowed him to inherit $7 million. His mother's three sisters want to stop Carman receiving any money from his grandfather’s estate.

Seventeen of the eight charges in the indictment relate to what prosecutors claim were fraudulent attempts to obtain money from his grandfather's estate and insurance companies. Carman is also accused of murdering his mother.

Through a spokesperson, Nikolas Kerest, Vermont U.S. attorney, declined to comment.

Federal Public Defender Michael Desautels, who is representing Carman, declined to comment on the charges.

Desautels stated that Desautels believed Desautels was in a strong state of mind and knew he had a team of lawyers to defend him.

Some law enforcement officers involved in the investigation suggested that the indictment could have been the result of new evidence not being released. Perhaps federal prosecutors in Vermont were less aggressive in gathering all evidence from a variety local, state, and federal agencies before presenting it to grand jurors.

Donald Melanson was the police chief in Windsor, Connecticut where Chakalos was murdered. "One of the issues, especially when it crosses state lines and who has the ability that bring all that together under one roof," he said. "And I believe that's why, and rightfully so," said Donald Melanson, chief of police in Windsor, Connecticut. He stated that the U.S. Attorney's Office took that responsibility and brought everything together.