ROCHESTER, N.Y. -- The former Cornell student accused of fatally shooting his father inside their Pittsford home was back in court Wednesday.

Charles Tan is accused of shooting his father, Jim Tan, 49, inside their home on Coachside Lane in Pittsford in February. He faces second degree murder charges. 

In court Wednesday, the judge ruled on two separate issues regarding evidence in the upcoming trial. One issue was a statement Tan made to police just after his arrest when deputies said Tan said he "had to do it." The judge ruled that statement will stand at trial.

Judge James Pampiano also ruled a surveillance camera picture of Tan attempting to buy a shotgun at an Ithaca Wal-Mart is admissible.

Prosecutors believe Tan was attempting to buy the gun days before the murder.

"Every trial is a construction of evidence in which you're trying to convey information to a jury. You try to have as many pieces of evidence that you possibly can that would allow the jury to make a decision based upon what you've gathered through law enforcement agents who have worked on the case. We always like to have as many pieces of evidence before trial starts," said prosecutor William Gargan.

"We're certainly satisfied with the first decision, we withdrew our request to suppress it. The second decision isn't a surprise and isn't particularly detrimental to our case," said Defense Attorney James Nobles.

Nobles said he will continue to build the case around an abusive father and husband. There's also been some question regarding the time frame of the death of Jim Tan. The medical examiner is expected to release the exact cause of death in mid-August. The judge asked for the report sooner, hoping attorneys could get the report by early August to better prepare for the trial.

Tan's murder trial is expected to begin in September.