Heidi Montag has allegedly hired a private investigator to find out whether her husband has been cheating on her.
The reality TV star is reportedly concerned her estranged spouse Spencer Pratt - who she split from in May - has been romancing other women.
An insider told RadarOnline.com: "She is very anxious to find out if her suspicions and the rumours are true, especially if he's spent any money on another woman.
"Heidi has hired a former member of the sheriff department, who now works as a private investigator, to look into it. It is really important to Heidi to find out if Spencer has been cheating on her."
Heidi isn't the only one with a suspicious mind.
Spencer allegedly believes his wife - who filed for a legal separation last week - is now seeing Marine-turned-bodyguard Cougar Zank, after he invited the 23-year-old blonde beauty to stay with him at his Malibu home following the couple's break-up.
The source said: "They are definitely friends, and I don't know if there is anything more to it than that, but Spencer believes there is. He's certain there is."
- Bang! Showbiz