Madeleine McCann's sister said her parents installed a panic alarm after an alleged stalker, who claimed to be her missing sibling, turned up at their home.Julia Wandelt turned up at the McCanns' property amid an alleged stalking campaign, which saw her sending unwanted emails and making numerous phone calls to the family, a court heard.The 24-year-old Polish national falsely claims to be Madeleine, who disappeared while on holiday with her family in Praia da Luz, Portugal, in 2007. Madeleine's younger sister, Amelie McCann, said her parents Kate and Gerry fitted a panic device, with a direct line to police, after Wandelt arrived at the family's home on December 7 last year. The 20-year-old, who was at university at the time of the visit, described it as an 'invasion' of their privacy.She told jurors at Leicester Crown Court: 'My parents told us there was a lot more security in place and if she ever came, there was an alarm we could press and alert the police.'Earlier, the court heard how Wandelt had messaged Miss McCann claiming she had memories of Madeleine's childhood, playing games with Amelie and her twin brother, Sean, before then claiming to have been trafficked to Poland. Miss McCann described the impact of the alleged messages had on her, telling the court it made her feel 'distressed' and 'uncomfortable'.