Washington ( CNN ) -- Investigators have uncovered no evidence to suggest a Maryland man taken in custody after allegedly threatening his workplace had acquired weapons illegally , a law enforcement official said Saturday . The man is undergoing a mental health evaluation at Anne Arundel Medical Center , officials said . The evaluation could take a week , according to Julie Parker , spokeswoman for Prince George 's County police . County authorities directed reporters to an official Twitter feed that identified the man as Neil Prescott . The post by the county state 's attorney 's office said no formal charges have been filed . The employee was in the process of being fired and was taken into custody Friday after a phone conversation with a supervisor , police said . According to police , the man called himself a `` joker '' and then said , `` I 'm gon na load my guns and blow everybody up . '' Police in the counties of Prince George 's and Anne Arundel acted on the alleged threat and the use of the word `` joker . '' The Joker is the nemesis of the comic character Batman and a character in the film the `` Dark Knight Rises . '' Police say the suspect in last Friday 's shooting inside a movie theater in Aurora , Colorado , where the film was being shown , identified himself afterward to police as `` the Joker . '' James Holmes has been arrested in the shooting , in which 12 people were killed and scores more wounded . `` An individual who was in the process of being fired was involved in two separate conversations with his supervisor , '' Prince George 's County Police Chief Mark Magaw told reporters . `` Both of those times and both of those telephone conversations he made significant threats to coming back and harming people at the business . '' Magaw added , `` In fact , he said ' I 'm a joker and I 'm gon na load my guns and blow everyone up . ' '' A search of the man 's apartment yielded 25 guns and thousands of rounds of ammunition , Magaw said . Magaw said police went Thursday afternoon to the man 's apartment in Crofton to interview him and found him wearing a T-shirt that said , `` Guns do n't kill people . I do . '' Later in the day , a district court judge issued a court order for the man to be held on an emergency commitment . `` We believe this was a significant threat based on some of the mental issues this individual has , the weapon capability he had ( and ) what he said to the employees at Pitney Bowes , '' Magaw said , referring to the business involved . Magaw said that , given Pitney Bowes ' status as a federal contractor , the man could be subject to federal charges .
Investigators have no information guns acquired illegally , official says . The FBI is investigating the incident as a possible hate crime and has asked for help from local law enforcement to identify suspects. The man calls himself a `` joker , '' police said .