Note: See https://github.com/pcbje/pymtgx for an improved approach.
Maltego and Casefile supports copying and pasting of GraphML. The aim of this project to ease the task of generating valid GraphML with Maltego's special needs from various dataformats.
Download the file maltego-importer.jar if you don't want to build the source yourself. You'll need to have Java 6 or higher installed.
Input format: Header based CSV
GangMember, Male, Female, LawOfficer Jon Doe,Some random guy,Some lady,Policeman
Input format: Value based CSV
Source type, Source value, Target type, Target value, Edge label
GangMember, Jon Doe, Male, Some random guy, Shoots Female, Some lady, Male, Some random guy, Sees Female, Some lady, LawOfficer, Policeman, Calls LawOfficer, Policeman, Male, Some random guy, Helps LawOfficer, Policeman, GangMember, Jon Doe, Arrests
Supported entity types are listed in MaltegoEntity.