Detective is one of the three skins released as part of the Ghost in the Machine offer. Detective is inspired by the character Batou from the anime Ghost in the Shell. It could be purchased as part of a coin deal from late March to early April 2017.
Detective could be purchased for $19.99 in a limited time deal that included the Cyber Agent skin and 50000 coins. It was not available for individual purchase and may not be available for purchase in the future.
Details of this skin may vary depending on location, platform or time.
Note: The Ghost in the Machine offer with the Detective skin was released again for a limited time in mid January 2019. This time the price was lowered to $9.99 and the package of coins was replaced with 1800 DNA. The deal still included the Cyber Agent skin.