Zaid al-Hilli was arrested Monday. Tuesday, he was released on bail until July 31, the Surrey police department said in a statement.
Police are investigating his potential role in the death of his brother, Saad al-Hilli, and three other people -- his sister-in-law, Iqba, her mother Suhaila al-Allaf, and French cyclist Sylvain Mollier, the BBC reported.
The victims were shot Sept. 5 while on vacation in the French Alps.
Investigators are investigating phone calls made to and from the suspect's home in the three-week period leading up to the vacation, the BBC said.
Zaid al-Hilli has denied fighting with his brother.