(Adds details on suspects, remarks from police chief, orchestra)
By Brendan O'Brien
MILWAUKEE, Feb 5 (Reuters) - Three people have been arrested in connection with the theft of a Stradivarius from a concert violinist in Wisconsin, but the multi-million dollar instrument remains missing, police said on Wednesday.
Investigators believe the suspects, two men and a woman, were acting on their own and that the 300-year-old violin is still in Milwaukee, Police Chief Edward Flynn told a news conference.
"This is not something that can easily be disposed of at some future date," Flynn said. "It's not valuable for a thief. It's only valuable to a collector."
The men, aged 36 and 41, and woman, 32, were taken into custody on Monday, Flynn said.
Chief Deputy Milwaukee County District Attorney Kent Lovern said a decision on whether they would be charged could be made as soon as Thursday.
The Stradivarius was stolen from violinist Frank Almond last week, when the culprits used a stun gun on the musician after a concert in suburban Milwaukee.
On Friday, an anonymous donor offered a $100,000 reward for information leading to the safe return of the violin, the Milwaukee Symphony Orchestra said.
The so-called Lipinski Stradivarius had been on loan indefinitely to Almond. Made in 1715, the instrument can be distinguished by unique striations on its back.
"It is our sincerest hope that the stolen Stradivarius is ultimately found so it may be enjoyed by the Milwaukee community for generations to come," the orchestra said in a statement.
The violin has a fair replacement value of $5 million for insurance purposes, according to Darnton & Hersh Fine Violins, which were designated curators of the instrument when it was loaned to Almond in 2008 by its owner.
The Lipinski is one of roughly 600 violins, violas and cellos still in existence that were built by the famed Italian artisan Antonio Stradivari.
A similar Stradivarius violin sold at auction for $2.3 million in December, according to the BBC. (Reporting By Brendan O'Brien; Editing by David Bailey and Gunna Dickson)