Detectives searching for a man over alleged drugs offences in Sussex said he tries to disguise himself by dressing as a woman.
Sussex Police said Christopher Brown often wears women's clothes while travelling on trains.
A £500 reward is on offer for information about the 36-year-old, who has the nicknames "Uncle" and "Macho".
Police said rail users hold the key to tracing Brown, who has a "high-pitched" voice.
Det Con Richard Slaughter said Mr Brown is wanted in connection with the alleged supply of Class A drugs in Worthing.
He added: "We are specifically appealing to rail users to think about whether they recognise this man, who has a very distinctive appearance."