PC Holly Britten, who is investigating, said: "We would like to speak to this man as we believe he may have information that could help with the investigation.
I am appealing for anyone who recognises this man, or has any other information about these offences to contact me via the Hertfordshire Constabulary non-emergency number 101, quoting crime reference C1/16/101. or report information online at www.contacthertspolice.uk/Report/Crime.