On the evening of March 9th two gunmen came into Café 56 in the Kleinbasel area of the city and fired shots, killing two people and leaving another in a serious condition.
The assailants went on the run after the shooting.
All three of the victims were Albanian.
In a statement on Wednesday morning the Basel public prosecutor said they had arrested a 41-year-old Albanian citizen “who is strongly suspected of being involved”. He has been placed in custody for three months.
Speaking to 20 Minuten, a commissioner from the Basel prosecutor's office said the arrest took place sometime in the last few weeks but would not say precisely when, for reasons related to the investigation.
A second suspect is still on the run.
The motive for the shooting has not yet been established and is the subject of a “difficult and extensive” investigation, said the prosecutor's statement.
Any link to drugs, as reported in Swiss media, has not yet been clarified.
Terrorism was quickly ruled out by police.
The 24-year-old Albanian critically injured in the shooting was released from hospital and subsequently arrested for immigration offences and deported, said the prosecutor's statement.