(CNN) The bomb that killed 22 people in Manchester was an intricate device that was likely put together by an experienced bomb-maker, who then sent a protégé to detonate it, experts say.

Here's what the pictures tell us about the suicide bombing outside the Ariana Grande concert:

The attacker

From the Times' pictures, it appears the attacker did not build the bomb, he was just the messenger, according to Bobby Chacon, a retired FBI agent.

Suicide bomber Salman Abedi

"The level of sophistication seems to indicate experience in putting a device like this together, which points toward a bomb-maker, and they are valuable members of these groups so it's usually a lower-level, less valuable member used to deliver the device," Chacon said.

Hamish de Bretton-Gordon, a former British army officer, said the bomber's background shows he did not have the ability to make such a sophisticated device.

"This is top bomb-maker work," de Bretton-Gordon said. "I would be very surprised if this boy had that capability and it seems more likely that he was a mule and was radicalized to be a suicide bomber. It's very likely there is a serious cell behind this attack."

An explosives expert told CNN terrorism analyst Paul Cruickshank that based on what was has been publicly revealed, there is a disconnect between the bomb design and the likely skill set of the suicide bomber, Salman Abedi

What we know: The bomb was packed with nails and screws, and rescuers have reported pulling them out of injured victims.

What we don't know: Is there a bomb-maker on the loose? Is he in the UK or elsewhere? How many suicide bomber protégés did he send out there?

Detonation device

If the device shown in the photos was the detonator, there probably was a backup person nearby to help set off the bomb, according to Chacon.

The New York Times says this is possibly the ignition switch that detonated the bomb.

"In some of these incidents, the mule is instructed to detonate when they are at a point of maximum impact and possibly sometimes there is someone standing by to detonate the device by remote means in the event the mule loses his/her nerve or the mule is intercepted by law enforcement before reaching his/her destination," Chacon said.

De Bretton-Gordon said the detonator is especially sophisticated, and not the work of an amateur.

What we know: At least one person is suspected of detonating the bomb, At least one person is suspected of detonating the bomb, 22-year-old Abedi

What we don't know: What type of bomb was it? If there was a backup person to detonate the bomb, is that person among the six arrested so far?

The battery

The battery in the picture was compact enough to stuff in the blue backpack, remnants of which are shown in the images, Chacon said.

A label, possibly from a 12-volt battery that may have been the power source for the bomb, The New York Times reported.

This image is of a shred of a backpack allegedly used in the Manchester attack.

"The battery is likely a motorcycle battery, which is about a third to a quarter the weight of a car battery," he said. "Still heavy, but certainly capable of being both hidden and carried in a backpack and provide enough energy to power the device."

The Times' photos appear to be taken by British authorities following the Manchester terror attack. The Greater Manchester Police declined to comment to CNN on the photographs.

What we know: The New York Times described the battery as a Yuasa 12-volt lead acid battery.

What we don't know: Was it the only power source? Why did the bomb-maker pick this particular type of battery?

The network

British authorities have said they believe Abedi was the bomber. But they have not ruled out other attackers, and have raided several homes in Manchester, looking for his associates.

"I think it's very clear that this is a network that we are investigating. And as I've said, it continues at a pace. There's extensive investigations going on and activity taking place across Greater Manchester as we speak," police Chief Ian Hopkins said.

The search for answers has taken investigators as far as Libya, where the attacker had roots and his brother was arrested.

Abedi allegedly had links to terror groups, and traveled with a younger brother to Libya, where their father apparently attempted to keep them from returning to the UK.

He was in Libya for three weeks and returned days before the attack, according to US military officials assigned to Africa.

Abedi's brother was arrested in Libya on Tuesday night on suspicion of links to ISIS, according to Libya's Special Deterrence Force.

CNN cannot independently verify the details from the militia. UK officials had no immediate comment on the reported arrest in Libya.

ISIS has gained a foothold in Libya as the government struggles to assume full command of the security situation.

ISIS claimed responsibility for the Manchester attack, even with no proven connection.

What we know: The suicide bomber grew up in Manchester with parents who fled from Libya.

What we don't know: Is the attack linked to ISIS, or the many ragtag militant groups in Libya? Are the attacker's associates in Libya or the UK?