There are Images uploaded to a certain website not linked to any accounts, just IP, linked in a case towards a federal case. can this evidence be inadmissible if the only proof is "IP : Picture". Prosecutor tagged all the pictures into evidence to the certain person.
This question needs more detail. As a cybersecurity professional I can provide some technical context around what I believe to be the situation.
While I do not know the legal precedence, technically, IP addresses cannot typically be attributed to an individual person. There are a number of reasons for this.
In a local network, IP addresses are not unique. Rather, they are distributed by the DHCP server, and are reassigned at intervals. Forensic attribution to an individual in most environments would require a DHCP log linking the IP to the machine’s MAC address, with time stamps that correlate to the individual’s logon to that machine at the same time.
If the IP correlation involves a VPN, it gets more difficult. I would need to know where the log/evidence was obtained to determine what the IPs in question actually correlate to. If the evidence was obtained in local area network of the suspect, the IP addresses are likely assigned by the DHCP server (see previous). If they are obtained after encryption in transit to decryption, then very little can be determined. If they were obtained at the VPN server log, these IPs likely belong to an ISP which in turn may or may not be able to show what machine initiated the conversation.
Digital photos often contain EXIF data, which is metadata about the photo. This data can contain details like, device make and model, sometimes location, time and date... If the defendant owns a Nikon such and such and the photo was taken with a Nikon such and such, and was uploaded using a VPN the defendant has an account with, and the defendant was in that location at the time and place of the photo... there may be enough there... but I’m not a lawyer.
I believe the discovery should include any EXIF metadata and logs to be used as evidence.
You may need a special technical whiteness to educate the court on what can and cannot be determined (technically) given the evidence. Things to consider for such a witness could include:
EXIF, forensic certification, network administration experience, VPN, TCPIP, OSI Model, Network Address Translation (NAT).
Again, nothing here should be considered legal advise. Seek professional legal counsel.