The motive behind the murder of 24-year-old Yale researcher Annie Le is still unclear and may never be known, New Haven, Connecticut, Police Chief James Lewis said Friday. Lab technician Raymond Clark III, 24, was arrested Thursday after police said his DNA matched evidence from the crime scene. Lewis said that investigators are still analyzing a plethora of evidence in an attempt to uncover more information. One theory points toward Clark’s alleged controlling tendencies, which included being possessive about the mice he watched over. Whether this would cause any kind of conflict with Le’s role as a researcher is unclear. Le’s body was found inside lab walls on the day she set to marry Columbia University grad student Jonathan Widawksy. On the same day, Clark casually played in a softball game while undercover police looked on. Le’s memorial will take place in her fiancé’s temple in Huntington, New York, on September 28. Clark is being held in Suffield, Connecticut, and his next court date is scheduled for October. His bail is set at $3 million.