Kiril Chelebiev, 24, has been accused of killing Medi, 25, at their flat in Bad Nauheim, Germany.
Officers who discovered Medi’s body said the flat looked like a “bloodbath”.
Police found her body after receiving reports that “something was not right” between the couple.
A friend told officers he was “worried about the both of them”.
Public prosecutor’s office spokesman Thomas Hauberger said: “You have to see it like this, an acquaintance of the couple reported to the police that he was worried about both of them.
“He told us about circumstances to which we had to listen attentively.
“On basis of that, we immediately started to search the flat.”
“The consequence was this massive violent crime”
Public prosecutor’s office spokesman Thomas Hauberger
He added: “We assume that it came to an argument in the flat.
“The consequence was this massive violent crime.”
Police launched a manhunt for Chelebiev, who is said to be psychotic.
The search went on for several tense hours and locals were warned to be vigilant.
He was later found and arrested in a local DIY store and has now been detained in a secure psychotic unit.
But Mr Hauberger did not reveal details of what officers found to that he did not endanger the ongoing investigation.