This is Tokyo's Shinjuku Ward.

S/ Witness / There were about three police cars, including unmarked ones. Police officers were there too. There seemed to be some kind of dispute and other things going on.

Police arrested two men on suspicion of preparing to carry out a robbery.

The Tokyo Metropolitan Police Department believes the suspects are part of a loosely organized crime group in which participants are usually not fixed and operate anonymously.

The police had received a tip about the possibility of a robbery targeting gold bars. 

S/ Reporter / Acting on the tip, officers were patrolling the area when they observed suspicious activity near this office.

On the morning of May 21, eight men arrived in two rental cars.

Officers saw six men going in and out of the office and acting suspiciously.

Two of them had batons in their hands.

In addition to the two arrested men, police are interviewing four individuals, including minors.

Police prevented this robbery from taking place.

But similar incidents are occurring in other parts of Japan as well.

In March and April, a store in Tokyo's Shinjuku Ward that buys high-end liquor was targeted in attempted theft and robbery incidents.

A car believed to have been used in these incidents was spotted near the scene of the robbery-murder case in Tochigi Prefecture.

The black van was captured on nearby security cameras.

Police suspect the perpetrators used it to conduct reconnaissance and make preparations before carrying out the robbery on May 14.

That was the day when a 69-year-old woman was killed at her home in Kaminokawa, Tochigi Prefecture.

Police have arrested four 16-year-old high school students who were allegedly in charge of carrying out the robbery and a married couple believed to have directed them.

Three days after the incident, investigators located the female suspect at a hotel in Yokohama along with her 7-month-old daughter.

Investigative sources said the hotel reservation was made under a third party's name.

The husband was apprehended separately at Haneda Airport in Tokyo.

The sources said he was likely planning to flee to another country after transiting through South Korea.

The four boys tasked with carrying out the robbery went to the targeted house by car.

After the crime, two of the teenagers got in the car and fled.

Of the remaining two, one was found by police about an hour later not far from the house.

Sources said the other three were later found in their respective home areas in Kanagawa Prefecture, with one of them tracked down at a restaurant where he was working part-time.

As the boys appeared to have returned to their everyday lives after the robbery-murder, they may not have received instructions on what to do after the incident.

On May 21, police searched the couple's apartment.

The suspects are said to have lived here with their infant daughter.

Were the three of them together on the day of the robbery-murder incident?

Police are continuing efforts to uncover the full details of the incident.

After about three hours, investigators left the apartment with boxes of confiscated items.