While Kourtney Kardashian is currently in Long Island to film another reality show "Kourtney & Khloé Take the Hamptons" with her younger sibling this summer, her $13.9 million luxury rental home was robbed of a briefcase containing thousands of dollars.

RadarOnline reported on Monday that Scott Disick filed a police report that $4,000 in cash was stolen from the $70,000 a month mansion he is staying at with his partner. It apparently took the 31-year-old reality star three whole days to notice the money was missing.

In detail, Disick made the complaint to Southampton Town Police on Jul. 8, claiming that an "unknown person unlawfully removed" the cash "from an attaché case that was stored in the bedroom."

According to the website, the case "is currently being classified as third-degree grand larceny, which is a felony." Detective Michael Smith also said that the mystery robbery is still being investigated.

This certainly is not the "Keeping Up With the Kardashians" members' first time getting robbed. Back in February, $50,000 in cash was stolen from Khloé's Calabasas home, shortly after $250,000 worth of jewelry went missing.

TMZ reported that the notorious clan thinks that "it's an inside job because this is the third time the family has been hit" and the thief is actually "someone close to them ... because they have access to the homes."

The latest robbery is believed to have taken place over a month ago around the Fourth of July weekend but not earlier than Jul. 1. Nothing else was reported stolen, and there was no indication of forced entry.