BERLIN (AP) — Investigators looking into the theft of hundreds of ancient gold coins from a German museum have found lumps of gold that appear to have resulted from part of the treasure being melted down, but still hold out hope of finding the rest intact, officials said Thursday.

Four suspects were arrested on Tuesday over the Nov. 22 break-in at the Celtic and Roman Museum in the Bavarian town of Manching in which 483 Celtic coins discovered during an archaeological dig in 1999 were stolen. The coins date to around 100 B.C.

Authorities said Thursday that DNA found on an object outside the museum, which they wouldn’t identify, led them to the suspects, three of whom they linked to a series of previous break-ins in Germany and neighboring Austria dating back to 2014. The Manching robbery appeared to be the alleged gang’s first targeting cultural treasures.

The coins and a lump of unworked gold were discovered during excavations of an ancient settlement in Manching, and authorities have said they are considered the biggest trove of Celtic gold found in the 20th century.

The deputy head of Bavaria’s state criminal police office, Guido Limmer, told reporters in Munich that authorities have examined 18 lumps of gold that were recovered this week. Each is believed to be the result of four coins being melted down, and Limmer said that the non-standard alloy largely matches that of the treasure, though a further analysis is ongoing.

“We know that about 70 gold coins have apparently been lost irretrievably in their cultural and historical significance,” said Bavaria’s state culture minister, Markus Blume. “But that means that of course there is still hope of perhaps being able to find the rest of the gold coins, and so the majority of the gold treasure.”

Searches for the missing objects were continuing in Mecklenburg-Western Pomerania state in northeastern Germany, where three of the suspects were arrested, and elsewhere.

The German suspects — a telecoms engineer, an accountant, a shop manager and a demolition firm employee — haven’t given any information to authorities since their arrest, officials said.

A judge on Wednesday ordered them kept in custody pending a possible indictment on charges of gang robbery, which can carry a prison sentence of up to 10 years. Three of them are also suspected of participating in 11 other robberies or attempted robberies between 2014 and 2022 in which supermarkets, a vehicle registration office and a casino were targeted.

Investigators have said that cables were cut at a telecommunications hub, knocking out local networks, before the Manching heist, and that the thieves got in and out of the museum in nine minutes during the night without triggering an alarm.

They said Thursday that similar methods were used in the other thefts, with the thieves wearing black overalls and using the same crowbars and a radio jammer to disrupt alarm systems and cutting phone cables. One of the thieves was conspicuously tall.

Some of the equipment apparently used was found in Tuesday’s raids on 28 properties, and one of the suspects was carrying the 18 lumps of gold in a plastic bag, officials said.

Investigators said vehicles rented this year by the suspects had been used to check out other possible targets in Germany, stopping near museums in Frankfurt, Idar-Oberstein, Trier and Pforzheim. Police moved in this week after being tipped off to a possible handover related to the Manching theft.