Authorities say the surviving mother initially described masked intruders before telling investigators she had tried to protect her son.

TUCSON, Ariz. — A 39-year-old man was arrested on suspicion of first-degree murder after authorities said he attacked both of his parents inside their Tucson-area home, leaving his 73-year-old father dead and his 72-year-old mother injured.

Pima County sheriff’s deputies identified the accused man as Tyler Lachmann and the dead man as his father, Chris Lachmann. Investigators said the violence began during the evening of June 28 and continued long enough to leave both parents with injuries to their faces, heads and arms. The surviving woman later told investigators that her son attacked the couple without warning, according to an interim criminal complaint described by local news organizations. The complaint does not identify a clear motive, and no motive had been publicly established in the sources reviewed for this report.

The first account given to authorities did not describe a family assault. Deputies were sent to the home before 12:30 p.m. June 29 after receiving what was initially reported as a possible cardiac arrest. When emergency personnel entered, they found Chris Lachmann unresponsive. Paramedics pronounced him dead at the scene. His wife was also inside the residence with visible injuries and was taken to a hospital. The Sheriff’s Department said the injuries observed on both parents were consistent with a violent attack rather than a medical emergency or an ordinary accident.

The surviving woman initially told deputies that two masked men had entered the home, robbed the couple and assaulted them, the complaint alleges. That statement gave investigators a possible home-invasion case involving unidentified attackers. During a later interview, however, she withdrew that account and said she had described masked intruders because she wanted to protect her son, according to the court filing. Authorities have not announced that the woman faces any charge arising from the initial report, and the public documents described in news reports do not explain when she changed her account or what questions led to the revised statement.

Her later description placed all three family members together inside the home on the night of the attack. According to the complaint, Tyler Lachmann repeatedly struck his mother and slammed her head against concrete. The document alleges that he then went after his father while the family was in the kitchen. The filing uses the phrase “without provocation” to describe the attack, but it does not provide a detailed narrative of what happened before the violence began. That description remains an allegation made during an active criminal case and has not been tested at trial.

After the assault stopped, the injured woman helped her husband reach a bedroom, according to the complaint. She removed his shirt, changed his pants and placed him in bed. She told investigators that she checked on him during the night before eventually going to sleep herself. The filing does not say whether she understood the seriousness of his injuries, whether either parent attempted to seek medical treatment during the night or whether the home had a working telephone within reach. It also does not state whether the husband was able to speak, walk independently or explain what he was feeling.

By the next morning, the woman found that her husband was no longer breathing and was cold to the touch, the complaint alleges. The call for emergency help brought deputies and paramedics to the residence and changed the case from a possible medical response into a homicide investigation. The precise cause and manner of Chris Lachmann’s death were not included in the initial public statements reviewed for this article. Authorities have said only that his injuries were consistent with an assault and that detectives believe the violence inside the home led to his death.

Homicide detectives identified the couple’s son as the suspected attacker and began searching for him. Members of the Pima County Sheriff’s Department Fugitive Investigations Unit located Tyler Lachmann later June 29 near Grant Road and Interstate 10, several miles south of the area where the attack was reported. He was taken into custody without any publicly reported additional violence and booked into the Pima County Adult Detention Complex. Authorities accused him of first-degree murder and domestic-violence vulnerable adult abuse.

The vulnerable-adult allegation reflects the ages and circumstances of the alleged victims, though the filing information publicly described by news outlets did not specify which subsection prosecutors intended to use. Arizona law defines vulnerable-adult abuse to include the intentional infliction of physical harm and allows felony charges when a person causes such an adult to suffer an injury. The classification can depend on the accused person’s mental state and whether the circumstances were likely to cause death or serious physical injury. Those legal elements must be proved in court and should not be treated as findings based only on an arrest.

A first-degree murder charge is among the most serious accusations available under Arizona law. The state statute includes killings allegedly committed intentionally or knowingly with premeditation, along with certain deaths that occur during specified felonies. Initial reports did not identify which murder theory prosecutors planned to pursue, nor did they describe evidence of planning before the attack. The filing of the charge does not mean Lachmann has been convicted. Prosecutors would be required to prove the necessary elements beyond a reasonable doubt if the case reaches trial.

News reports citing the complaint said Lachmann was already on pretrial release in a separate felony matter when his parents were attacked. In that earlier case, he was accused of pointing a firearm at his girlfriend’s mother on April 29 and threatening to kill her. The status of that allegation, including whether it had been resolved or remained pending when the homicide case began, was not fully detailed in the reviewed reports. It is a separate accusation and cannot be used by itself to establish that he committed the later offenses involving his parents.

The surviving mother reportedly told prosecutors that her son had mental health problems. The available documents do not identify a diagnosis, treatment history or evaluation, and they do not establish whether any condition played a role in the alleged attack. Mental illness does not automatically determine criminal responsibility or competency. Those questions require separate legal and medical findings. No verified public record reviewed for this article indicated that a court had reached such a finding in Lachmann’s case.

Initial reporting said Lachmann was being held without bond and had been assigned a July 6 bond hearing and a July 10 preliminary hearing. Those dates have passed, but the publicly accessible reports reviewed for this update did not reliably establish what occurred at either proceeding or whether the case was later transferred, continued or formally indicted. Court schedules and custody decisions can change, and the original hearing dates should not be treated as proof that the proceedings happened as first planned.

The Sheriff’s Department described the investigation as ongoing. Authorities had not publicly released a full autopsy report, a detailed account of physical evidence recovered from the home or a final explanation for why the alleged assault began. Lachmann remains presumed innocent unless he is convicted in court.

Author note: Last updated July 28, 2026.