Police on Long Island say they are looking for a "neutral-colored" SUV as part of their investigation into the shooting at Oheka Castle, and sources tell NBC 4 New York that surveillance video shows him being gunned down.

Sources familiar with the investigation say the video doesn't clearly identify the suspect in Monday's shooting of the castle owner, Gary Melius.

Melius was wounded by a gunshot to his head as he sat in his car outside the upscale wedding venue and hotel in Huntington. Police say the bullet did not penetrate his skull, but a source told NBC 4 New York that the gunman "tried to kill him. This was a serious attempt on his life."

Detectives are looking into Melius' personal and professional dealings as part of their investigation.

On Tuesday, police set up a checkpoint near the shooting scene.

Melius is celebrated as a philanthropist and also has donated hundreds of thousands to politicians.

Oheka Castle says on its website that it can accommodate up to 1,000 wedding guests.

In addition to weddings, the castle hosts fundraisers, galas and numerous other high-profile events.

The oldest member of the Jonas Brothers, Kevin Jonas, was married at the 109,000-square-foot French-style chateau in 2009. Former President Bill Clinton officiated the wedding of Anthony Weiner, ex- congressman and mayoral candidate, at the castle in 2010.