Wan, which represents more than 15,000 newspapers worldwide, expressed serious concern at the murder and its apparent link to Bhatnagar's reporting activities. ``We respectfully but strongly urge you to ensure that this crime is thoroughly investigated and that those responsible are brought to justice,'' Wan said in a letter to Prime Minister Atal Behari Vajpayee. The Paris-based Wan, the Global Association of the Newspaper industry promotes press freedom world-wide. Its membership includes 57 national newspaper publisher associations, individual newspaper executives in 90 countries, 17 news agencies and seven regional press groups.