Across  
5. A person who approaches an intelligence agency with the intent of being recruited to spy   
against his or her own country  
11. Spy catching  
13. Slang used by British Intelligence for a spy  
14. An agent who pays spies and bribes government officials  
15. A false passport or visa  
  
Down  
1. Unknown to enemy intelligence  
2. the original message before encryption  
3. Murdered  
4. Bodyguard  
6. Headquarters of any espionage service  
7. The science of secret writing in all its forms  
8. An agent whom a service will permit to be detected and arrested so as to protect more   
valuable spies  
9. An agent of one organization sent to gain information by working for the enemy  
10. A system of disguising a message by replacing its letters with other letters or numbers  
12. A spy who creates false passports, visas, diplomas and other documents