text: Rocker Richie Sambora is being investigated by police over claims he 'threatened to kill' his former fashion designer lover. The ex Bon Jovi guitarist, 55, allegedly told former business partner Nikki Lund he would 'dig a hole in the desert and bury her', Daily Mail Online can exclusively reveal. Sambora is said to have made the chilling threat during a blazing telephone argument on March 19. His shaken former flame decided to report the allegation to authorities a week later. Police in the wealthy Los Angeles suburb of Calabasas confirmed to Daily Mail Online that Sambora is a 'person of interest' in an active investigation into criminal threats. Scroll down for video . Everything was rosy between the ex Bon Jovi guitarist and his lover and business partner Nikki Lund last July. But Lund has claimed in a statement to police that Sambora recently threatened her saying he would 'dig a hole in the desert and bury her,' Daily Mail Online can exclusively reveal. The rock star is believed to be on vacation in Bora Bora with his ex-wife Heather Locklear and daughter Ava but faces questioning when he returns. Lund, 33, founded the Nikki Rich clothing line with Sambora and confessed last year that the pair had been having an on-off personal relationship for eight years. When their affair ended it plunged the business partnership into turmoil, just as the duo were preparing to open a boutique on swank Robertson Boulevard. Sambora's alleged threat came just days after Lund launched her first signature solo show at the opening of LA fashion week on March 18. 'They are in the midst of unraveling their fashion business Nikki Rich,' a source told Daily Mail Online. 'Things have become very bitter in recent weeks. 'The threat happened in the midst of Nikki launching her solo line. Richie apparently went mad on the phone at her and threatened to kill her. 'He said words to the effect that he was going to dig a hole in the desert and bury her.' Nikki, a close childhood friend of Kim Kardashian, filed a report Wednesday night with detectives from the Lost Hills Sheriff's Station. Back to back: The couple posed for the cover of the new edition of  LA Fashion Magazine before they went their separate ways . 'She held off going to cops hoping that the situation would resolve itself,' added the source. But after advice from lawyers and business associates she made the report. 'Richie has been drinking heavily for months and acting erratically . 'He has threatened violence in the past.' Nikki and Kim K are friends from way back . Lieutenant Jennifer Seetoo confirmed to Daily Mail Online that Sambora is a person of interest in the case. Under Californian law making criminal threats can be a felony offence punishable by up to four years in jail. 'A report was taken regarding criminal threats,' Lieutenant Seetoo said. 'It's an active investigation.' A representative of Mr. Sambora said there was no truth in Nikki Lund's claims. 'This is a cluster of fabricated lies in retaliation for Mr Sambora's decision to cease further funding of the unprofitable partnership, plain and simple,' said the rep. Sambora suddenly quit Bon Jovi during their 2013 world tour because of 'personal issues'. The New York Post later reported that Jon Bon Jovi had kicked out his longtime songwriting partner due to substance abuse issues. Sambora and Lund reportedly began their romance in 2006 - a year before his divorce from Dynasty actress Locklear was finalized. Denise Richards dated Sambora . Sambora is believed to be in Bora Bora with his ex-wife Heather Locklear and their daughter Ava . They are said to have carried on seeing each other despite Sambora going on to date another Hollywood beauty, Denise Richards. The long-time fling became public last December when Lund was doing publicity for the new fashion line. The curvy blonde confessed to Playboy TV: 'He's amazing in bed ... how could you stay away from the guy?' Their joint venture collapsed at the last moment, however, despite the pair appearing on billboards together and on the cover of Los Angeles Fashion magazine. Sambora is now dating Australian guitarist Orianthi despite a 26-year age difference. Lund's attorney declined to comment on the complaint. Current squeeze: Sambora is now dating Australian guitarist Orianthi despite a 26-year age difference .
target: Richie Sambora is about to be quizzed by police over claims he 'threatened to kill' his former fashion designer lover and business partner .
  She is a childhood friend of Kim Kardashian .
  Police in the wealthy Los Angeles suburb of Calabasas confirmed Sambora is a 'person of interest' in an active investigation into criminal threats .
  Their joint venture collapsed at the last moment and Nikki went out on her own .
  Rock star is believed to be on vacation in Bora Bora with his ex-wife Heather Locklear and daughter Ava .