How to Collect and Preserve Evidence for Your Criminal Defence Lawyer

Why Early Evidence Collection Matters

When you are charged with a criminal offence, the clock starts ticking on evidence. Surveillance footage is overwritten — most commercial systems retain recordings for only 14 to 30 days. Witnesses move, change phone numbers, or simply forget details. Injuries heal. Physical evidence degrades. Social media posts are deleted.

The Crown has the resources of the police to investigate and gather evidence on their behalf. Your defence lawyer needs your active participation to build the strongest possible case. While the Crown is required to provide disclosure of its evidence, there is often critical evidence that only you can identify, locate, and preserve — evidence the police may not have collected because it does not support their theory of the case.

This article explains what evidence to collect, how to preserve it properly, and what pitfalls to avoid.

Types of Evidence to Collect

Photographs and Video

If the allegations involve physical harm, property damage, or events at a specific location, photographic and video evidence can be invaluable.

Photographs of injuries. If you were injured during the incident — particularly in self-defence or mutual combat situations — photograph your injuries immediately and again over the following days as they develop. Include close-ups and wider shots that show context. Bruises, scratches, and swelling that are visible shortly after an incident may fade within days.

Photographs of the scene. If the location of the incident is relevant, take photographs that capture the layout, lighting conditions, sight lines, and any physical evidence (broken objects, marks on walls, positions of furniture). If the incident happened at night, photograph the scene at the same time of day to show actual lighting conditions.

Surveillance footage. Identify any businesses, residences, or public cameras that may have captured the incident or your movements before or after. Make a list of every potential camera location and provide it to your lawyer immediately. Your lawyer or a private investigator can then contact the owners to request preservation of the footage before it is overwritten.

Time is critical with surveillance footage. If you were charged last week and there is a camera at a neighbouring business that may have recorded the incident, that footage may already be gone.

Witness Information

Witnesses are among the most important sources of evidence in a criminal case, and they are also among the most perishable. People who saw what happened, heard relevant conversations, or can speak to your character may be difficult to locate weeks or months later.

Eyewitnesses. If anyone witnessed the incident — bystanders, neighbours, coworkers, friends — record their full name, phone number, email address, and home address. Do this as soon as possible after the event, while you still remember who was present.

Character witnesses. Your lawyer may need character witnesses at sentencing or at a bail hearing. Employers, religious leaders, coaches, teachers, family friends, and community members who can speak to your character and reputation should be identified early. Provide your lawyer with their contact information and a brief note about your relationship with each person.

Alibi witnesses. If you were not at the location where the alleged offence occurred, identify anyone who can confirm your whereabouts. This might be a coworker who saw you at the office, a friend you were with, or a family member. Alibi evidence is subject to specific notice requirements in Ontario, so providing this information to your lawyer early is essential.

Text Messages, Emails, and Communications

Digital communications are frequently relevant in criminal cases. Text messages between the accused and the complainant can provide crucial context — showing the nature of the relationship, prior threats or harassment by the complainant, consent discussions, or inconsistencies with the complainant’s version of events.

Save everything. Do not delete any text messages, emails, direct messages, voicemails, or other communications that are even remotely connected to the incident or the people involved. This includes messages sent before, during, and after the alleged offence.

Take screenshots. Screenshots preserve the content even if the original message is later deleted by the other party. When screenshotting text conversations, capture the entire thread — not just selected messages — to avoid allegations that messages were taken out of context. Include timestamps and the contact name or phone number in each screenshot.

Export data where possible. Many messaging platforms allow you to export entire conversation histories. WhatsApp, Facebook Messenger, and other platforms have export functions that create a complete record. Your lawyer or a digital forensics professional can advise on the best method for each platform.

For a more detailed discussion of digital evidence, see our article on collecting digital evidence.

Medical Records

If you sustained injuries during the incident, medical records documenting those injuries can be powerful evidence. Visit a doctor or hospital as soon as possible after the incident, even if your injuries seem minor. Medical records created contemporaneously with the event carry significant weight.

Medical records are also relevant if you have a mental health condition, addiction, or other health issue that is connected to the alleged offence. These records can support arguments at bail hearings and at sentencing.

Request copies of your medical records directly from your healthcare providers and provide them to your lawyer.

Employment and Education Records

Records demonstrating stable employment, educational achievement, and community involvement are valuable for bail hearings, sentencing submissions, and plea negotiations. Gather:

• Letters from employers confirming your employment status, tenure, and performance
• Pay stubs or employment contracts
• School transcripts or enrollment confirmation
• Certificates of completion for any courses, programs, or training

Financial Records

In some cases — particularly those involving fraud, theft, or allegations of financial motive — financial records are directly relevant to the merits of the case. Even in other cases, financial records can demonstrate stability and responsibility for bail and sentencing purposes.

Keep records of rent or mortgage payments, utility bills, child support payments, and other financial obligations that demonstrate you are a responsible, contributing member of the community.

Receipts and Documentation Supporting an Alibi

If your defence involves being somewhere other than the alleged crime scene, gather every piece of documentation that places you elsewhere. This includes:

• Debit or credit card transaction records (with timestamps)
• Transit passes or ride-share receipts (Uber, Lyft)
• Parking receipts
• Gym check-in records
• Loyalty program records (coffee shops, grocery stores)
• GPS data from your phone or vehicle

These records can corroborate alibi witness testimony and create a paper trail that is difficult to dispute.

How to Preserve Digital Evidence

Do Not Delete Anything

This cannot be overstated. Do not delete any messages, photos, videos, social media posts, or app data from your phone or computer. Even information that you think is harmful should be preserved. Deleting evidence can result in additional criminal charges (obstruction of justice) and will severely undermine your credibility if discovered.

Save Metadata

Digital files contain metadata — information about when and where a photo was taken, when a message was sent, or when a document was created. This metadata can be just as important as the content itself. When saving files, use methods that preserve metadata:

• Forward emails to yourself rather than copying and pasting the text
• Save original photo files rather than screenshots of photos
• Export data from apps using their built-in export features rather than manual copying

Back Up Everything

Create backups of all relevant digital evidence. Save copies to a cloud storage service, an external hard drive, or both. Phones break, get lost, or are sometimes seized by police. Having backup copies ensures the evidence is not lost.

Consider a Forensic Preservation

In cases where digital evidence is likely to be central to the defence, your lawyer may recommend retaining a digital forensics professional to create a forensic image of your phone or computer. This creates a complete, verifiable copy of all data on the device that can be presented in court.

Physical Evidence

Clothing and Objects

If the incident involved physical contact, your clothing may contain important evidence — DNA, fibres, blood, or other trace evidence. Do not wash the clothes you were wearing during the incident. Place them in a paper bag (not plastic, which can promote degradation of biological evidence) and store them in a safe location. Inform your lawyer that you have preserved the clothing.

Similarly, if any objects are relevant to the incident — a damaged phone, a weapon, personal belongings — preserve them without cleaning or altering them.

Scene Evidence

If you have access to the scene of the incident and it has not been secured by police, document it thoroughly with photographs and video before anything changes. Note the positions of objects, the condition of doors and windows, and any damage.

What NOT to Do

Do Not Contact the Complainant

If your bail conditions include a no-contact order with the complainant, do not contact them under any circumstances — not directly, not through friends, not through social media, and not through family members. Breaching a no-contact condition is a separate criminal offence and will severely damage your case.

Even if there is no formal no-contact order, contacting the complainant after being charged is almost always inadvisable. It can be characterized as witness intimidation or obstruction of justice.

Do Not Post on Social Media

After being charged, your social media activity can and will be scrutinized. Do not post about the case, the complainant, the police, or the court process. Do not post photos of yourself at parties, drinking, or engaging in activities that contradict the image you want to present to the court.

Ideally, reduce your social media activity to a minimum until the case is resolved. Anything you post can be used against you.

Understand Recording Laws

In Canada, the Criminal Code at section 184 permits one-party consent recording — meaning you can legally record a conversation that you are a part of, without telling the other person. However, you cannot record a conversation between two other people that you are not participating in.

Be cautious with recordings. While a recording of a conversation where the complainant admits to lying could be powerful evidence, the circumstances of the recording will be scrutinized. Discuss any recordings with your lawyer before making them.

Do Not Investigate the Complainant

While it may be tempting to conduct your own investigation — checking the complainant’s social media, talking to their friends, visiting places they frequent — this kind of activity can be construed as harassment or stalking, particularly in domestic assault or criminal harassment cases. Leave the investigation to your lawyer and any private investigator they retain.

Working with Private Investigators

In some cases, your defence lawyer may recommend retaining a private investigator to gather evidence. Private investigators can:

• Locate and interview witnesses
• Obtain surveillance footage from businesses
• Document scene conditions
• Conduct background research on witnesses
• Serve subpoenas

Private investigators operate under legal and ethical constraints. They cannot trespass, harass witnesses, or misrepresent themselves. Your lawyer will direct the investigator’s work to ensure everything is done properly and that the evidence gathered is admissible in court.

Organizing Evidence for Your Lawyer

When you meet with your lawyer, having your evidence organized saves time and ensures nothing is overlooked. Consider the following approach:

1. Create a timeline. Write out a chronological account of the events leading up to, during, and after the alleged offence. Include dates, times, and locations.
2. Organize by category. Group your evidence into categories: photographs, witness information, digital communications, documents, physical evidence.
3. Provide context. For each piece of evidence, include a brief note explaining what it is, why it is relevant, and how you obtained it.
4. Bring everything to your first meeting. Do not filter evidence based on what you think is important. Let your lawyer assess the relevance and value of each item.

The Bottom Line

Your active participation in evidence collection can make a meaningful difference in the outcome of your case. The earlier you start and the more thorough you are, the stronger your defence will be.

Do not assume the police have collected all relevant evidence. Do not assume your lawyer can find everything without your help. And do not wait — the passage of time is the enemy of evidence.

Contact Mor Fisher LLP

If you have been charged with a criminal offence in Ontario, the criminal defence lawyers at Mor Fisher LLP are ready to help. We will guide you through the evidence collection process and build the strongest possible defence on your behalf.

Call us at 705-721-6642 or contact us online for a free consultation. We serve clients across Barrie, Toronto, and Central Ontario.