Of course they can and do monitor messages, but they have to legally do it with warrants. If they have probable cause something criminal is happening. FBI does monitoring of online predators too. They can contact the staff of Kik to release information. Facebook is contacted by tons of law enforcement agencies all the time and they cooperate so Kik is no different. Same with Snapchat, they all co-operate with the law because they have to. Some messaging services like Facebook’s even go further and actually automatically notify staff if certain red flag wording is typed. In other words, the messaging service itself has built in automated monitoring that automatically contacts the Staff if something is wrong. Below is links to news articles of real people arrested for doing bad things on in Kik.
Va. man arrested for raping teen he met on KIK
http://wtvr.com/2013/10/29/kik-rape-arrest/ PEDOPHILES are using a relatively new smartphone application to try and coerce young children into performing sex acts, police have warned. http://m.theaustralian.com.au/technology/pedophiles-coerce-kids-using-kik-smartphone-app/story-e6frgakx-1226608130656