Oland, 46, is accused of killing his father, prominent New Brunswick businessman Richard Oland, in 2011.
The public hearing, which started six months ago, is designed to test the strength of the prosecution's case and determine whether there's enough evidence to proceed to a trial.
Two days have been set aside for the Crown and defence to summarize their cases.
There is a publication ban on evidence presented during the inquiry, such as the testimony of witnesses and details about exhibits.
The ban, which was requested by the defence, may only be lifted if Dennis Oland is discharged or at the end of a trial, if a trial is ordered.
Judge Ronald LeBlanc, who was brought in from Bathurst, N.B., to hear the case, could deliver his decision as soon as Thursday.
Connie Oland — Dennis's mother and Richard's widow — issued a statement last year declaring her son's innocence.
"We know that he will be found innocent in an objective and fair process in a court of law," the statement from Connie Oland, Dennis's wife, Lisa Oland, and sisters Lisa Bustin and Jacqueline Walsh stated.
His extended family has also stood by him since the beginning. Derek Oland — Dennis's uncle and Richard's brother — issued a statement saying that they believe Dennis is innocent, and that they would support him and his family through the legal proceedings.
The preliminary inquiry began May 12 and was originally expected to take about 20 non-consecutive days, but had to be extended several times and has been sitting on and off since then.
The court has heard from dozens of witnesses, including police officers and medical experts.
Richard Oland, 69, was found dead in his uptown Saint John office on July 7, 2011. At the time of his death, he was the president of Far End Corp., an investment firm.
Dennis, an investment adviser and his only son, was charged more than two years later, on Nov. 13, 2013.
After spending six nights in custody, Oland was released on a $50,000 surety and has been living in the community under several conditions, including that he advise police of any change of address or any travel outside New Brunswick. He was also ordered to surrender his passport.
Oland is being represented by lawyers Alan Gold of Toronto and Gary Miller of Fredericton.
The Crown prosecutors handling the file are John Henheffer, Patrick Wilbur and Derek Weaver.